Here's what I do: I've prepared a gprs file on my Linux box. First I turn off Cellular data in the UI, then I adb push it to the phone, then adb shell to the phone, then sudo cp the gprs file to /var/lib/ofono/###########/gprs. When I turn Cellular data back on, the gprs file on the phone is immediately overwritten with the original one, that I get when I Reset All APN Settings in the UI. Where are those settings coming from? From the cell provider (Google Fi)? Some other file on the phone? So, I can't use the UI to set the APN I want and I can't hand code it in the gprs file. What's it gonna take?