I don’t have much to offer on this question because I don’t run my machine with a Raspberry Pi. Hopefully someone who does will chime in. I just wanted to say that maybe you should look into gSender Edge. I have read on here that it has a headless mode and that sounds like what your looking for. Searching the forum for gSender headless yields some results that may be useful.
This one in particular, is from the Sienci team.
Maybe this will get you started on the right path. Good day to ya!
Michael