Hello gentlemen, I recently succes to build ASL on my debian bullseye ARM64 (VM embedded on French ISP router).
You can find my fork on : GitHub - Artemia76/ASL-Asterisk at aarch64-portage
This fork change build script enable arm64 (thanks to encbar5) and my hack on direct IO access (sys/io.h) what doesn’t exist on arm64 architecture. For dahdi , I use the official asterisk/dahdi-linux github project
I already push my pull request on official github project.
I didn’t use debian packaging for this, only source build install. But another OM succes to change debian prepare script to enable bulleye post installation github F4HWD/ASL-Asterisk
I Think a merge of both forks can produce a working ASL-Asterisk on bulleye arm64 