so they embeded a separate launcher?? welp, it's also not necessary, the EOS backend does not need the Epic launcher. As far as I know, the only cross platform/cross play back end is EOS. Sony have their own PC/PSN cross play in example of Helldivers 2. Capcom have their backend and the up coming Monster Hunter Wild is their first title to support cross play. (it was always separated in their past games.) Some big Chinese/Korean dev have their proprietary cross platform backend to support their mobile/console/PC games. (like Genshin)
If you do know any 3rd party cross play back end service please let me know.
Yeah, just get a PS5 slim? should be fine if you don't want the disc, or buy used PS5. My launch PS5 is still doing really well. But I stopped playing any multiplayer game on it and stopped PS Plus.