not aware of any major breakage. In fact, my laptop is currently running on that branch for testing for a few days.

re. the one you're linking here, we agreed to accept this for now: https://github.com/NixOS/nixpkgs/pull/379542#issuecomment-3699768829
Let's not forget that the interface in question (<termio.h>) has been obsolete since the late 90s and from what I've seent his only affects non-native workloads (and apparently even target architectures only that we don't provide full support for).