In short, we haven't found many bugs, but it also wasn't just recompile on a new platform.

We've seen test failures like https://github.com/python/cpython/issues/151040

And perf support needs to be tested and merged https://github.com/python/cpython/issues/121201

Overall though, fairly smooth sailing as you say.

The reason RISC-V wasn't already supported is a mix of lacking hardware access for build bots and committers willing to pledge time to support it.