It’s niche maybe, but I don’t think you’re the only one. It came up in a thread just a few months ago, for example:
https://community.fly.io/t/podman-and-gvisor/26529
The new multi-container Machines, if you haven’t seen them before, solve most of the problems that people were trying to address with containerd. (And, originally, they were the basis of Fly.io’s own Kubernetes implementation.) It might help to say a little more about what remainder those don’t provide, that you still need…