Why isn't libkrun good enough for hosted stuff? I use it as a podman backend in a microservice architecture.

Firecracker has more tooling for the orchestration layer that manages many sandboxes at once. Stuff like K8S integration, an external REST API control plane, more first-class support for snapshotting, etc.

You'd have to build more of that with libkrun

The core tech of both are great though.