This might be obvious but there are a lot of Europeans on tindie. You might want to reach out to some of them that make things you find interesting.

They’re often desperate communities based around specific hardware. Like the Amstrad CPC, BBC Micro, Atari ST or other retro computers. Plenty in retro consoles too.

I’ve not found a single forum where people lurk but rather independent message boards. I believe there’s a few Facebook Groups, possibly Redit too, but I don’t personally use Facebook nor Redit. You generally find them when looking to do something interesting on a specific device.

However if anyone knows of a more centralised place then I’d be interest to know too.