For reference for other purist UHD snobs like me;
https://www.digiraw.com/DVD-4K-Bluray-ripping-service/4K-UHD-ripping-service/the-real-or-fake-4K-list/
I think people are forgetting the DS part of the question
DS are very cheap second hand and all the game cartridges work in offline mode natively. If you haven’t ever owned a DS before you need to pickup a few 3DS XL models ASAP and catch up on that whole generation of gaming!
As for switch people are right below, if you want longterm playability you might need to emulate on a different device like a steam deck. Some switch games need that online ‘phone home’ to download the game
Does Plex do photos or just videos?