> (pretty sure it's a problem with my hand-assembled hardware, in fairness)

Certainly could be the case. I've spent more time than I want to admit chasing down what was ultimately a loose wire.

For what it's worth, you can get a cheap ESP32 module and basic IR sensor modules for a few bucks on amazon [0]. As long as you have a basic USB <-> TLL/Serial adapter, you should be able to install ESPHome on that. The module that's on that particular board does not have a ton of room so keep the ESPHome config simple and to the point.

It's a few dozen lines of yaml total to get a basic IR signal decode/dump tool: [1]

[0]: https://www.amazon.com/HiLetgo-Infrared-Transmitter-Receiver...

[1]: https://esphome.io/guides/setting_up_rmt_devices#remote-sett...