This repo uses the stock YOLOv5 to create a people counter on a Raspberry Pi 3. It takes a picture from the pi camera (or possibly USB cam will work too, but not tested), and runs YOLOv5 on it.
In then get the tags we're interested in (persons and pizzas -- unfortunately we didn't get it to count pizzas....).
It displays the number of people on a 7 segment display connected to the GPIO pins (the middle pins to +3.3V, the rest of the pins have to be mapped in count.py; these pins were chosen so that they are all on inner-row of the GPIO headers), as a hex value between 0 and F.
Obviously from here you can do what you want with the data (e.g. send it to discord server mqtt server, after which it goes to discord).
The system runs on balena (make sure you use 64-bit and -- so far the system only runs on bare metal (without balena).balenaOS 2.94.4; there is an issue with at least some newer versions.
The system was created for internal use in Hackerspace Trójmiasto.
More info (blog posts / photo's / etc) will follow.