If I flash Telus SM-G920W8 firmware on my Bell SM-G920W8 device would there be any incompatibility issues?
The frequencies are the same from what I just looked up I have put v410 att firmware on my uk410 and it work but I never had mobile data on it so I'm not sure about data but I'm going to say your good to do it just proceed with caution have the correct firmware that's supposed to be on the phone and if u have a custom recovery make a back up and give it a try I'm not saying it will work but it's a possibility and if other dont work try a custom ROM for the firmware you want to use I tried downloading and installing the stock AT&T firmware online UK 410 and it wouldn't work but cyanogen14 for the v410 flashed just fine to my uk410
In stack exchange's infinite wisdom, I can post answers, but not comments. So what follows should be a comment, but blame stack exchange, not me:
You won't run into incompatibility issues with Android. The phone will function, since that's the exact hardware that ROM is supposed to run on. It's been a long time since I've ran a carrier's ROM or had a locked phone, but you should be able to add the APN for your carrier in the data settings and it'll work on that end too.