2 years effort (full-time last 8 months) into a microkernel/OS for the PinePhone. 10k Zig LoC, with some global assembly. Just about completed the UI, navigation, and various sensors. Next will be the beeps 
and then some apps (maybe a games SDK if I can access OpenGL ES).
Zig has been an amazing fit for this project, the code is easy on the eyes, the binary tiny, and the whole thing is booting into a pair of demo apps in under 800ms! and that is still only using 1 of the 4 cores.
Sorry to say I’ll be sticking with older Zig version. It seems a better fit, and I’m not keen on the new IoC/DI design direction that Zig has now taken. But thanks for the amazing journey from 0.7, and wishing you the best of luck.
And a huge thank-you for the community that is so professional, welcoming and supportive. This OS might be my final tech project, since AI is destroying much of what I love about the industry, but glad that there is some kinda sane refuge here. I love reading all the projects that everyone is working on, and amazes me still how inventive we can be when working together.