This project seems pretty cool!
I’m quite happy about alternate compilers cropping up.
I think one thing that will cause trouble is that currently the language is pretty complex, but unspecced. Furthermore, certain things get changed often – Rust is not very forward compatible. By this I mean that the language evolves rapidly, and certain “implementation details” like inference change every now and then too. While this is all backwards compatible, these changes may make more things compile, which you’ll have to notice and add to the GCC backend. This can be tracked by following the RFCs, but many such changes are not RFCd (e.g. a tweak to make inference better).
This won’t be a blocker, but it will be a challenge. I imagine as the GCC frontend matures we’ll get better about communicating such changes and involving GCC folks in decisions.
I’m not sure if you were referring to financial support or general tech/community support. I don’t know anything about the financial side, but I expect the Rust community and teams to be quite positive about this; and we can probably change our processes a bit to make it easier for you (e.g. by being more careful about noting forwards-incompatible changes).