The main thing matchlock adds over general-purpose vm/container tooling is agent specific network and filesystem (wip) controls, so if an agent goes rogue it can't exfiltrate your API keys, and damage largely mitigated. You'd have to build all of that yourself on top of LXD (possibly similar to matchlock).

There's also the DX side - OCI image support, highly programmable, fuse for workspace sharing. It runs on both linux and mac with a unified interface, so you get the same/similar experience locally on a Mac as you do on a linux workstation.

Mostly it's built for the purpose of "running `claude --dangerously-skip-permissions` safely" use case rather than being a general hypervisor.