When I pick this up again, I'm looking at the 2022-04-04 release of Bullseye, which should have the 5.15.xx kernel.? Buster has a release of 4.19 kernel I'll test also.
Describe "works okay" for your environment.? Where does it fall apart and what are you using?
I used to run 64 bit only Slackware 13.?