Thanks for the well thought out answer. It's very possible it was a combination of all of them. I'm sure I've left a phone out in the sun for a bit before. This is the first phone I've used for an AR game but it's been used/played for a few months now. And first phone I've done wireless charging on and probably the last lol.
I think with all of this, I'm at least a little relieved that it could have been a combination of things rather than one specific thing and that it could have just been a fluke. With this in mind, I'm going to be foregoing wireless charging technology for now and be more careful about having my phone out in the sun. And since my phone is in pristine condition otherwise, maybe I can recoup some money for parts...