I need a new phone, and I have some requirements that are so specific I'm now out of options and need help.

The requirements:
1. Snapdragon 820 or better
2. I use Wind Mobile in Toronto so it must support HSPA on band 4 and be carrier-unlocked.
3. Android, and that I can find a working root on xda-developers.
4. 5" or larger screen
5. This is the killer: I must be able to confirm that it can run this game smoothly without lag. It is so demanding it actually killed my last phone, a Zenfone 2.

The closest things that fit this bill are Pixel and OnePlus 3. I'm open to other options, just don't tell me Galaxy S7; its KNOX is a total turn-off (not rootable without consequences). Best Buy is useless because they don't sell Pixel off-contract and OP3 is online only. I'll need to test hands-on for the last point and may likely need to return the tester so preferably if you guys can find me a place that accept returns.