I have it working on Windows 11 22H2 with OBS 30.0.2 and RICOH THETA UVC 3.0.0.
Try flipping the Device between different cameras in the OBS interface. Often the video stream won’t appear for me unless I select a different camera in OBS first, then go back to RICOH THETA UVC device.
set up OBS to use the webcam on your local computer, then when it is running, flip to the RICOH THETA UVC device using the OBS dropdown menu in the OBS settings