I was looking at this reddit post - Game benchmarks for M1 Mac mini with 8gb ram inside!.
Per one MBA user on Diablo 3 forums
You might update to 11.0.1 if that doesn't work try the PB of 11.1 its what I am using.
Still not loading for me. The Mac mini M1 has a different graphic card and the MacBook Air user wasn’t on the beta, so I’m still saying:
Diablo 3 doesn’t work on a MBA with M1 chip under Big Sur Beta 11.1.