One of the good things about open source software is that you don’t have to wait for a software company to produce an M1 binary. The minute the M1 C++ compiler is available for download, any SC user can get the compiler and the source code and try to build it.
In my rudimentary tests, performance of our (intel) BigSur build is quite good on M1, similar with the latest intel chips for scsynth. SC startup seems a little slower though. I’ve also tried compiling SC natively and that process had some caveats. It looks like the native build runs maybe 10-15% faster than running through Rosetta2, but my testing was very non-scientific, so we need to see how the performance looks like in the real world.