This is incredibly helpful information! Last few questions:
What carrier are you using? AT&T or T-Mobile?
Do you have access to 5G?
Do you happen to know what bands your model has? (If you aren't sure and actually feel like going through the trouble of finding out, you can use LTE Discovery to find out. No need to do so if you don't want to.)
I'm on AT&T. My model is ASUS_I005DA. It was listed as the International version. Came with a UK charger brick. It says "ROG" on the back and doesn't say "Tencent Games." After the most recent update, I gained access to VoLTE. However, my model is only connecting to LTE via bands 2 and 4. This lines up with the bands listed by the seller. I would like to know if ASUS_I005DC has more bands that are compatible with US GSM networks. 5G would be incredible.