Interestingly the author has a startup revolving around this technology. Their webpage has some info: https://multikernel.io/

The author (Cong Wang) is building all sorts of neat stuff. Recently, they built kernelscript: https://github.com/multikernel/kernelscript -- another DSL for BPF that's much more powerful than the C alternatives, without the complexity of C BPF. Previously, they were at Bytedance, so there's a lot of hope that they understand the complexities of "production".

I see. Even better than Xen, but needs much more memory than all the kvm instances. And as I heard memory is the real deal for mass hosters, not speed. So I am sceptical. I also don't understand how it handles concurrent writes and states of shared hardware. Seems like a lot of overhead compared to kvm or Xen.