All of my frames have mountings for full-size (28mm) FPV cameras. I've got a couple of Foxeer mini-sized (21mm) cams which come with a bracket that bulks them out to 28mm. But the whole industry seems to be moving towards micro cameras to the point that even minis are getting a little bit thin on the ground. Caddx don't even seem to make anything bigger than a micro any more.

So how are people mounting micro cameras? Particularly people with full-size frames?

I mostly see printed mounts anymore. Plug your frame into thingiverse and see what you get.

Frames are going micro too. I buy the camera for the frame. I really haven't replaced the camera on the older full size frames. I have just used an adapter in the past.