Yes I'd be surprised if the fiddly open-source parts of non-XCode toolchains are reliably being built for M1 (or ARM in general) yet. An interesting downside to the M1 macs for sure, at least for a while. Thanks for bringing it up.
Homebrew works great on M1. I use it a lot and have only had one problem (some gem on ruby doesn't compile properly) where I've had to switch to the x86 version, but it all seems to work side by side perfectly and you can just prefix any command with _arch x86-64_ if you do need x86.
If you want to get an M1 Mac for development, I haven't found too many things that don't work and most work very well. The compile speed on even an M1 MacBook Air is incredible.