DroidCam OBS
Similar to DroidCamX, DroidCam OBS is a combination of an iOS and Android app and OBS plugin which combine to allow the user to turn their phone into a video source in OBS. The phone can connect over either wifi or USB. Unlike DroidCamX it is compatible with Windows, macOS and Linux and there is no limit (aside from possible network issues) to the number of DroidCam OBS videos that can be running.
COST:
Free version with limitations
Full version $9.99CAD