get bpy python working by:

$HOME/git/tools/blender_git/build_linux_v4.1/bin/4.1/python/bin/python3.11 -m venv venv
source venv/bin/activate
pip install bpy

to install mathutils, this was necessary for me:

sudo xbps-install -Sy python3.11-devel
CFLAGS=$(python3.11-config --cflags) LDFLAGS=$(python3.11-config --ldflags) pip install mathutils

install addon:

cd <root directory>
ln -s $(pwd) $HOME/git/tools/blender_git/build_linux_v4.1/bin/4.1/scripts/addons/abc3d

get blender addon path:

bpy.utils.script_paths()

then check it for the addons directory

addons dir:

~/git/tools/blender_git/build_linux_v4.1/bin/4.1/scripts/addons/

addon data:

~/.config/blender/4.1/datafiles

reload addon in blender:

F3 -> "reload scripts"