During the July 2025 London Apple Admins meet-up, I presented on using Homebridge to add non-HomeKit stuff to HomeKit.
Below is a link to the talk, and a link to the video for the whole event. I seem to have misplaced my slides, but really all you need is: homebridge.io.
See below for a link to the video, the GitHub repo with a PDF of the slides.. as well as a link to video for all talks from there meet-up.
Talk Video
GitHub Repo
https://github.com/macmule/talks/tree/main/laa-jul-2025