A PID tune is pointless if the printer is not reading temperature correctly. It is for gauging how much power to send to the heat cartridge, it does not effect temperature readings.
Yes, thermal compound was used in appropriate places.
I can interact with my printer via klipperscreen or the mainsail web UI. Both give the same temperature reading. I don't have any way outside of Klipper to talk to the printer.
I might try installing marlin on my previous board to see what the gets me, if anything.