Nix and Guix.
Good luck convincing people to switch!
But they’re roughly the same paradigm as docker, right? My understanding of the Nix approach is that it’s still reproducing most of a user land/filesystem in a captive/separate/sandbox environment. Like, docker is using namespaces for more stuff, Nix has a heavier emphasis on reproducibility/determinism, but … they’re both still throwing in the towel on deploying directly on the underlying OS’s userland (unless you go all the way to nixOS) and shipping what amounts to a filesystem in a box, no?
Trying to convince people usually makes any resistance worse.
Using it, solving problems with it, and building a real community around it tend to make a much greater impact in the long run.