But that version of alt store does not support installing uyouplus. At least I have not been able to add the repo.
I’m trying to imagine voluntarily buying a device that all but prohibits you from choosing the software you run on it. A limit of 2-3 apps, which have to be re-signed weekly by a desktop server, to me that doesn’t count as “supporting sideloading.” Maybe technically. What a joke.
not on US devices without jailbreaking, but I think you can on EU devices.
You can on any iOS device without jailbreaking. Look into AltStore or Sidestore. The caveat is that you can only sign 3 apps at a time, and must resign these apps every week - which is done over your WiFi to a PC running AltStore server.
If you have a $99/year Apple developer account, you can use AltStore to sign as many apps as you like, and you only need to resign once per year.