Ruby, which is what Brew uses, has already been ported over to ARM. There is no *official* support yet basically because they're still testing packages for compatibility. This is why the official advice from the devs is to run Terminal under Rosetta 2.
Personally I am holding off for a bit simply because I'm not sure how this slightly hacky solution will leave me once official ARM support is included in Brew binaries. It looks like I'd have to uninstall Brew as well as all Brew packages then reinstall them again in a normal (non-Rosetta) Terminal. I'd rather just wait for things to be official so there's no headaches down the road.
But that's just me. I don't foresee support taking too long considering it's only a matter of testing packages, not a whole port that still needs to be done.