So I purchased a Logitech C920 webcam, which has UVC support. The USB ID is 046d:0892.
My primary driver is an X200, which is great for my typical uses, but horrible for transcoding. But guvcview is able to record 720p raw (no transcoding) at a full 30fps (well, just slightly under), with audio. So I could offload transcoding to another machine (either pre-record, or stream).
This works under GNU Guix System with entirely free software and zero setup.
Follow
And one of my golden retrievers decided to try to eat it while I wasn't looking. So it's also durable, though I don't recommend buying for that use case.
(Sorry for the delete & repost---I left a "not" in the original message that completely negated what I was trying to say.)
