My day job is basically a DevOps/SRE type role, so it’s unsurprising that I’ve built a lot of monitoring into the phone. Here’s a sample of a discharge/charge cycle of the battery:
You can see that heat dissipation during charging is something I still have to work on. 57 degrees C isn’t fatal, but it’s not ideal either.  I have discovered that it runs hotter when enclosed in the phone, so improving airflow might be a good option. I am also thinking about ways to thermally couple the computer to the metal base of the phone, as that’s a pretty good heatsink.