I'd like to share a project I've been working on in my free time for fun: a small dbms engine with support of transactions with ACID properties resistant to restarts/failures (just like any other dbms). If you find dbms development topic interesting and would like to participate you are welcome I can give a short intro as well/answer questions if you have any.
Link: https://github.com/stencillogic/db-core
Is this on crates.io? If not, I'd recommend uploading it. That will get you documentation published for free, which will make it way easier for users or potential contributors to get up to speed.