3G generally refers to the 3rd generation of cellular communication (the frequencies and ways a phone communicates with cell phone towers). Phones can’t really be updated between them, the modems in them are made to support what they support and thats it.
3G is being shutdown gradually world wide to make room for better 5G speed and coverage. 5G is the newest generation of cell communication.
3G networks debut in 2001 and 2002. 5G networks started being deployed in 2019.
I mostly stick to things in the repos, if theres something I want that’s not yet packaged I package it myself because Gentoo packages are fancy bash scripts with libraries (eclasses) to handle the normal make && make install sort of things for most build systems