Warning: long-a** post ahead.
TLDR: there are none and there won't be any (most likely) any time soon.
This is a tricky subject. I'm assuming there's no harm in rephrasing your original title into a bit more "abstract" yet a whole lot more useful "non-X resources to learn Y" where X is a concrete specific tool / approach / philosophy (in this case: Rust) with regards to Y - the overall domain / theory / praxis within a given field of human endeavour (here: low-level/system programming as a whole).
The reasons it's a tricky one aren't that obvious. For one: the cost-to-benefit analysis in the short-term / immediate (the only real guiding force in most of the contemporary self-obsessed "market") is heavily skewed towards X over Y nowadays. Most couldn't care less about X or Y - to begin with. They're only in it for Z - the personal gain with the better job with the higher pay with the stock.
If all you're looking for is a comfy little MAMAA's spot for your backside (Z), it makes less sense to spend all the time and effort in the world to turn yourself into the most knowledgeable expert in the domain of your choice as a whole (Y), than it does to put sound-proof vanta black blinders on and proceed to happily specialize in one specific tool currently in-demand: be it C/C#/C++/Rust (X).
Perhaps, if the people in charge of hiring would make an effort in looking for Y as opposed to X, we'd see somewhat of a different picture. Which brings us to the point number two: the recruiting process. You'd think by this time most would have figured out that it's the depth of knowledge that matters, not the amount of checkboxes you can tick off next to any potential candidate's name.
Unfortunately, both for the people they are in charge of hiring and the company employing them as a whole: most recruiters are just as obsessed - with their own little Z, in their own little world, where their own little fears and desires and ambitions and concerns drive all of their day-to-day. Trying not to get fired, impressing their boss, ticking the same few lists of checkboxes, occassionally acquainting themselves with some "industry-proven" practices, looking smart while at it.
Filtering out "10+ years of experience with Rust"? Easy enough. Seeing how (poorly) someone handles some meaningless, convoluted, utterly detached from any real-world scenario Le3TC0De problem? No problem, boss. Making sure the potential hire understands the difference in between processes and threads and data races and CPU caching and low-level sync primitives? ... . Let's circle back on that. In the meantime, here is the "industry standard" that Google uses today ...
Which brings us the "educators". You'd think they, out of all people, would understand that it's not about the specific tool you're using (X) - be it C/C#/C++/Rust - as much as it is about your overall understanding of the capabilities and limitations and pros and cons of each (Y) - which are quite universal and don't require nearly as much as cramming of all the endless edge cases associated with any one particular environment: at least not if you understand the essentials well enough.
Unfortunately for you - and rather fortunately for quite a few of them - their own interests and incentives and goals (Z) strike again. Even if they know enough to be able to teach you about it (which would only apply to a select few individuals out there, nowadays): why would they willingly reveal it all in one go, if they can keep feeding you bits and pieces, here and there, that never quite fit and "click" into any proper and coherent whole, yet keep you firmly glued to their "content"?
Why risk losing you as a potential buyer to one of their courses luring you with some loud and juicy "learn X and land THE $100K JOBZ!!!" headline? Why turn you into a potential "competitor"?
Lastly: the "community". It hardly matters what exact PL we're talking about, though in the context of Rust in particular a few more aspects come into play. You'd have to search for quite some time before you stumble upon a plumber who would swear by any particular brand of utensils and call whoever uses anything other than his personal favorite a whole bunch of cute little nicknames.
Then again, a plumber's job doesn't depend nearly as much upon his expertise with/love of one particular brand as a programmer's job does on his own with/of his given PL of choice. Add to that any additional moral and ethical aspect at large ("it is right/wrong to use Rust/C as it will/won't help you avoid countless bugs and memory issues") and you'll get yourself a solid recipe for a cult.
In the context of the subject at hand - what matters the most here are, once again, the incentives. People who like Rust want to continue using Rust. People who like C++ want to continue using C++. Same goes for people who have a soft spot for C# and JS and Python and Haskell. If you're strongly biased inclined towards any of them, chances are: you don't simply want to continue using it yourself. You want to get as many people to use it as well. The more people you "recruit" in your camp, the higher the chances of it not only surviving - but growing and spreading, after all.
Suppose you now wish to write a book that "bridges the gap". You pack it to the brim with all the gems and nuggets and essentials which are universal to all the low-level code: be it C or C++ or Rust or even D. It's likely that it'll take you quite some time to finish it. In the meantime, you probably still have to eat. Which means you'll either have to work on it in your spare time alone, or take a break from any full-time retirement altogether to focus on and ask some people for support.
Want to go the hobby route? Well, that's cute. There's a ton of material you'll have to scavenge all over, make sure all of its builds - for every language and every OS you want to showcase - cross reference it up and again, proofread, etc. It's a gargantuan amount of work, and if at any point your full-time gig comes into jeopardy (maybe 'cause, dunno - layoffs?) the whole thing will just stop.
If it's the last option you settle on: who exactly are you going to ask? How many people do you think will be out there ready for you to offer your "encyclopedia of systems programming" to them? Out of those, how many would even consider paying you for it? How would they justify this purchase?
Do you expect the TikTok gen to take an in interest it, with their whole non-existent attention span of a brain-fried goldfish or less? The "me wanna job; me see job offer with X in title; me wanna learn X now" folks - for them to stop and think and reflect and reconsider priorities in life? The people in the camp of Rust or C++ or C who have already "made their choice"? Who is it going to be?
Combine all the points above and you'll get yourself a fairly exhaustive answer as to why:
will likely never see the light of the day. To be clear: I would love to see it happen, myself. My faith in the homo sapiens' ability to follow anything but their basic instinct and/or personal interest heavily incentivized by the lure of the clear-cut personal reward is a bit too low at this point, though.
Your best bet is to try and [1] get acquainted with as many languages as you possibly can, unless it's some obscure throw-away academic research project ; [2] avoid falling into any single camp yourself ; and [3] use every opportunity to experiment and explore and find out as much as you can about whatever it is you're currently working with. It's also the best way to make things stick.
Working through a pre-made path someone else has made for you will never teach you quite as much as you can teach yourself by building something that genuinely interests you on its own.
Do keep in mind, as well, than sooner or later you will have to specialize. People who focus on back-end infrastructure won't have the same amount of understanding for all the bits and pieces that go into making GPU's do fancy stuff - something which game programmers might very well be required to learn. Learn and explore and discover and experiment. Just don't over-stretch yourself.