Ppsspp

[LunaMoo]

PSP games can be bought digitally from PS Store, from anyone that still sells PSP UMD's. In the first case you will need to download a pkg file, then just extract a PBP file from it and that's pretty much best disc backup format you can get which PPSSPP can read. In case of UMD's, you will have to use real PSP with custom firmware to dump the game(by mounting UMD drive for usb) to another device.

As far as this project is involved, there are no other ways.