I read this a couple of times and I can't tell how they are sponsoring the Rust Project. Apparently Rust uses some AWS services, are they now getting these for free, is that the sponsorship?

The rust devs recompile a huge chunk of the entire rust ecosystem to make sure new compiler versions don't break things.

I can't imagine something like this being even close to feasible in the C++ ecosystem; there is too little standardization of build tooling, too much brittle/broken code.

Still it's not cheap and Amazon is paying, bless their hearts and excess compute capacity when it's not Christmas.