Not the OP, but I just downloaded the latest stub from an M2 MacBook Air using Safari and it appears to be an x86_64-only binary:

  % file /Volumes/Steam/Steam.app/Contents/MacOS/steam_osx 
  /Volumes/Steam/Steam.app/Contents/MacOS/steam_osx: Mach-O universal binary with 1 architecture: [x86_64:Mach-O 64-bit executable x86_64]
  /Volumes/Steam/Steam.app/Contents/MacOS/steam_osx (for architecture x86_64): Mach-O 64-bit executable x86_64