How/where can I find replacements for these 'wheel bearing caps'?

Metal dust shields would be the common name to the extent there is one. The usual protocol is to handle them with care and never remove them, because they're difficult to replace. The OEM hub manufacturers don't produce a vast number of different ones, so one option can be finding a bike shop with bins of used parts or dead wheels and trying to cannibalize some that match. Wheels Mfg does produce some cones that come with them, and there are generic axle kits that come with random sized ones, but getting it to work is all kind of a hail mary, especially if you need to order them. There are no standards as such for their ID, OD, depth, etc.

As long as they're not torn, working them back into shape looks possible from the pictures. They don't have to be pretty. One approach is finding a socket that's the right size and smacking them down flat again, then working the edges into shape with a hammer and the socket on the other side to act as a mandrel.

If you do find some to transplant, use a vise or suitably sized deep socket to provide support on the flat side, then gently tap them off the cone you found them on and onto the new one. You usually have to go back and adjust the depth a bit manually to make it the right height off the seal interface and prevent rubbing.