> Unless someone does a great deal of effort to port all of those environments that people want (nodejs, modern python, etc) you're going to be stuck using a VM and losing a lot of the benefit.

It should not be a huge deal of effort since as you mention the plan9 syscall API is simpler than on Linux. The added plan9 support could then also serve as a kind of "toy" backend that could make the rest of the code more understandable in other ways.

I'd even argue that OP's early experiment with such a port of tailscale shows precisely such an outcome.