It would be interesting to see a detailed security assessment of this. Would it provide security improvements over docker?

Docker is the wrong thing to compare against, especially considering it is an application and not a technology; the technology would be containerization. This competes against hardware virtualization support, if anything.

If you want some security improvements, move from docker to podman rootless + distroless containers.

If you need more security/isolation, go to a VM or bare metal.