Curious if there are any D users here who try to stay within that intersection?
The bigger problem is guaranteeing concurrency safety, which you can only provide with nonblocking IO. Everybody loves blocks though, so that's far away.
That depends. It is really a Hard NO for GC?
Crystal is low level enough with a GC and people have written a complete OS with it. On my mobile now so I can't provide link. But it was featured on HN a while ago.