RX100 VII on macOS 11 doesn't work with the recommended settings, quelle surprise from Sony software. The €9 capture card I read about here works perfectly and at higher res.
a5100 on macOS 10.14.6 does not work too. Skype and Photo Booth do not detect camera at all, Google Meet sees video source but it contains only test pattern. I also tried to make it work on Windows VM with USB passthrough but no luck and in the end, just like you, I went with cheap capture card and that works great.
Which capture card are you using? I couldn't find mentions to it in this thread.