I want to try to make a 3D Homebrew game for PSP (Playstation Portable). I read that there were games made with UE2 and UE3 on this platform. Can I do something similar with UE4 or UE5?
UE4 and UE5 don’t have the PSP binaries so out of the box, no. You may be able to modify UE3 binaries to work with UE4 but I’m not confident in that approach.