I have been working along these same lines, but am still waiting for a Canon lens adapter to arrive so I can have decent glass in front of the sensor (the basic is OK, but I have a few Canon lenses that knock it out of the park).
Meanwhile, I have a slightly tweaked version of uvc-gadget that does not jump to 100% CPU when the camera is off: https://github.com/rcarmo/uvc-gadget
I tried the K&F Concept lens adapter, but the big caveat is the sensor size difference, so effectively you get a huge zoom factor. Using the Kit lens from my Canon, I either need to put the camera module meters away from my face or meeting participants are only going to see my nose. :)
I have a 18-55(?) which is blatantly overkill but might be easier to tune in that regard. Biggest concern I have right now is aperture size, and I certainly don't expect things to be perfect on the first try :)
The crop factor of this camera is about 5.6, so 18 mm behaves like a 105 mm telephoto. For a portrait shot the camera needs to be about 3-4 meters away from you.
Meanwhile, I have a slightly tweaked version of uvc-gadget that does not jump to 100% CPU when the camera is off: https://github.com/rcarmo/uvc-gadget