I've got this working well on a RPi4 running LE11 nightly.
/storage/.config/autostart.sh reads as
Then to get audio output from squeezelite wait 5-10s after playing audio from kodi then turn on the squeezelite device.
To get audio output back to kodi turn off the squeezelite device and wait 5-10s.
You do need to follow that routine of turning the squeezelite device on/off in your main squeezebox remote/control page, but once that is sorted it all works remarkably well. Potentially better than when I was running the now unmaintained Squeezebox plugin.