Uim apps are for oneplus to connect remotely to help fix phone same as a pc tech would do when u ring to fix a pc they connect remotely.
Not even close. UIM = User Identity Module. R-UIM is a form of SIM commonly used in Asia. com.qualcomm.qti.uim contains a service called "RemoteSimLockService", so I assume the UIM packages all apply to SIM as well as R-UIM.
The UIM package is the only one that runs in the background, so it's the only one that provides much benefit from disabling, at the cost of remote SIM-lock functionality; a tradeoff I consider worth it, but others may not. This is why it's important to label things and know what you're disabling.
Lte broadcast lol who streams there phone to a tv these days
AFAIK, Broadcasts are mainly used for
Emergency Alerts. Like tornado/tsunami warnings and the like. Potentially quite important
Location services if you notice i remove every location app except fused location. My location works fine.
If you use a tool to inspect system processes you'd see that com.qualcomm.location runs even if disabled/"uninstalled" (adb uninstall is not proper uninstall); I don't think disabling/"uninstalling" it does anything, making such a change/debloat pointless.
I install and remove apps everyday and have had no problems when i remove documentsui none what so every.
Disabling documentsui mainly breaks things related to backing up app settings to files. Nova Launcher is an example of a very common app that can't setting backup/restore anymore with documentsui disabled.