Oh I'd agree and gVisor provides (IMO) a smaller attack surface than a default runc container.

With that said both options, and indeed hypervisor based isolation, are generally one security flaw away from a breakout vulnerability, so the only difference in that respect is the incidence of those flaws.

My experience of people's expectations of container isolation is perhaps somewhat different to yours, which is what prompted my initial comment.

It's all too common (in my experience) to see container isolation dismissed using that "containers don't contain" trope, and for me that feels frustrating as the real picture is much more nuanced than that.

It's all about choosing the right isolation technology for a) a given workload and b) a given threat model/attack surface.

There are tradeoffs (both in terms of performance, and in terms of flexibility) in replacing the runc layer with a different container runtime. Sometimes those will make sense, other times not so much :)

All that said I'm very excited to see more options here, as it'll give everyone the choice of what mechanism works for them for specific workloads.