If you can pop in a sim and it's not asking for a code go through the apps and disable carrier app, Network companion and all boost overlay apps by turning off the open by default switches, dial *#*#4636#*#* go to NR options from the top option and pick auto, in my are it switches from sa to nsa, depending on the carrier you might want to make sure your carrier is using NR for calls, make sure its not saying Rcc in error, with Metro you can use ipv6 basic sim settings or T-Mobile apn in settings, under the 4636 hidden menu set the network from NR, LTE, Wcdma to NR,LTE,gsm,wcdma or unknown. Basically Unknown is the best option because if you switch carriers it will pick the correct configuration, if said new carrier uses LTE for voice calls it might be needed to disable VoNR so your not burning data on calls, at this point my ram is at 3 or 4 instead of 5 with the boost settings, rcs chats are registered and my signal is maxed out using 5GUC. It just takes some research and it can be run perfectly on the crappy boost firmware, it just takes some time to work with. If you get stuck make sure you are backing up everything and if you have problems do a wipe from the fast boot and start over. Look up and do your research on the stuff you turn off, virus total might show you some apps not being utilized. This is the best I can do at this point.
My new, unlocked Edge+ that I am planning on activating on T-M is arriving this weekend.
Maybe a build# would help to be added to this thread, most ppl will probably use that build for the best performance. I'd appreciate it even though my boost firmware is up and working on Metro I haven't got a security update since 2/23 all these comments on settings I've made are going to apply to the U.S. networks.