Does GrapheneOS not support this? I am not seeing a Webcam option under Use USB for

EDIT: https://discuss.grapheneos.org/d/8672-phone-as-webcam/3

Seemingly it is still a pending feature, that will be included with the December quarterly feature release (“QPR1”). The only people who are using it now on their phones are running QPR1 betas, which I think first began releasing in September.