Ah yeah, MartyPC and Haiku are on my list as well. Microcontrollers don't excite me that much anymore though, after having worked with them professionally (both using them and creating them) for decades
My fear with new projects that seem interesting, though, is that they're slop. I read about a new project and for a split-second I think 'oh, that's cool' and then the realisation sinks in. 'Oh, it's probably slop, isn't it?'
I could just ask gloriouscow (npub1dhl…ud8y) for MartyPC for eg, but it seems rude... And what about Haiku? Do they have a policy? I don't know. Help!