I wonder how Distrobox compares to nix shell.

If I understand correctly, Distrobox makes it convenient to launch (and destroy) lightweight VMs on demand, while nix shell makes it convenient to drop into a shell with some package installed. The documentation around nix has unfortunately been unapproachable in my experience.

Of course, Flatpaks+Podman will be a learning curve, but I'm eager to try Silverblue+Distrobox on one of my computers.