It is working, finally.
I had issues transferring the watch to GOS, due to missing permissions and ended up factory resetting the watch, after I tried to connect it to stock P8P, which also did not work correctly. I then gave a lot permissions to play services, play store and Google app on GOS.
After the reset I set it the watch up again with stock OS on P8P and then transferred it to GOS P10F again, which worked on the third try. You have to be patient as it took a few minutes, but now the watch is fully connected to GOS and has the digital key stored on the watch! I just did a test drive without any key except the one on the watch.
Still, UWB is not working, which is kind of annoying. Maybe someone has a fix for that.
Next thing is to revoke the not needed permissions on GOS.