Recently bought a 2nd hand Pixel 8, just to try graphene os.
I put my work sim (Ooredoo Qatar) which has a generous plan. worked out most of the things with time, but has not found a way to get the hotspot to work.
I went through forums and found that similar things happen. Has someone found a fix? I don't think the carrier has placed a restriction, as it does work with other devices. For me it is currently click and turn off in few seconds, showing "Error" in the expanded settings.