i’d suggest starting by finding out what package in your distro actually decides where audio goes - mostly it is pulseaudio (older) or pipewire (newer).

depending on the details of how your distro and the dongle work, it could either be a simple “pactl set-default-sink <headset-name>”, or a more complicated set of udev rules or pipewire/wireplumber scripts.

note that distros using pipewire still often support a lot of pactl commands, so it may be worth looking at the simple option even when not using pulseaudio.