Currently there's only an x86_64 wheel. You could either build a separate arm64 wheel, or build a universal2 wheel. RobotPy currently builds universal2 wheels instead of separate wheels.
IIRC, I think universal2 is first supported in Python 3.9, and you're currently building 3.8 abi wheels -- but RobotPy currently only supports 3.9+, so that should be fine.