I did, just to see if it would work.
It did.
I created a second "hard" partition on my 2021 MacBook Pro 14".
Formatted to HFS+ (NOT APFS).
It works.
But... I find I don't really need it, because the MBP isn't really my "main Mac" and not much stuff is on it.
I reckon I might be the only Apple Silicon MacBook Pro user in this forum who has an HFS+ partition on his internal SSD...