Yes, pretty much, except for one detail:
> That runs the codex OCI in a qemu microvm.
AFAIU it's actually the other way around: krun spawns a libkrun-based (not QEMU-based) VM inside a crun container. Source: https://github.com/libkrun/libkrun/discussions/538#discussio...
So with your solution you get the additional security benefit of containerizing the hypervisor on the host.