With some help from my friend ChatGPT, some debugging, and MQTT, I was able to use my Novation Launchkey 25 MIDI controller to control the lights (or anything in HA, really).
I'm planning to do a more sophisticated project out of this, maybe an .exe and make the script run in the background etc. But a quick MVP at least.
Here's a quick writeup as well if anyone's intrested. https://github.com/slungs/midi2mqtt