I created an NES thermometer.

Reference: https://erspicu.github.io/AprVisual/s1a/aprnes-thermometer-tool.html

The custom version of aprnes included there is an implementation designed to verify the "Open Bus" analog-style rapid simulation; it accepts temperature parameters, allowing the test ROM to measure the temperature via the Open Bus.

Temperature readings may vary across different emulators.

If you have a vintage NES console that exhibits the full characteristics of the Open Bus, you might want to give it a try.