Is there a community specific to FOSS or just general privacy oriented IoT? With plenty of hardware discussion along with software. Routers, piholes, Meshtastic, anything IoT but open source. If it touches a network but you want it to do something it doesn’t. Flashing a doorbell camera with FOSS firmware. Hosting media servers on your phones Hotspot. Loading gcode to a printer from anywhere. There are so many things and possibilities.
If there isn’t someone should start one, OpenIoT or something catchy and relevant.
People like this usually hang around the microcontroller spaces since these people will almost always make a case with a 3D printer and order ESPs from Aliexpress and program their own device/install Tasmota or something. Some people maintain a happy medium with purchasing pre-built hardware and running FOSS on them, but IMO the real fun is when you do most of it yourself. Not discounting how good OEM hardware can be in terms of overall functionality, of course.
The downside to writing your own code is maintaining its security which is a pain though.
I don’t think you’ll find many people like the type you’re looking for here outside of the few in the communities I mentioned previously. You’ll have to look at other forums, unfortunately.