I made a thing last night cause I was bored. it’s pretty much useless but it works. hard part was getting the i2c bit working. Basically what I have here is, a raspberry pi nano running esphome to connect 12 buttons and 32 leds to home assistant. the leds run thru 2n2222a transistors to take the current load off the mcp23017 gpio extenders. 1k ohm resistors for each led because that’s just what I have on a bulk roll and use a lot on leds. :) The gpio extenders and transistors get power off the 5v rail so as to not overload the 3.3v rail of the nano. not even sure how much current it is.

It’s not much but it’s mine. ;)

The Pico Project