They are so-so. Well, they are much-much better than any webcam, of course, but 1080p is almost the same as 720p on them. So as a budget thingie it'll work, but Elgato's adapter is much better, of course.
I saw a video where Elgato Camlink opened up, is just a chinese card repackaged with the Elgato logo, 99% similar internally to the cheap knockoffs.
Can't find it again to link it to...
8 layer pcb with custom fpga hardware, doesnt look all that cheap chinese knockoff to me
Can't find the video atm, or remember what product it did show, but it was posted in the last 2-3 months and it concerned a similarly on-demand item -- and the "repackaging" brand was respected by creators...