Sounds like a poster child for LXC containerization with Proxmox — all the host-level management of a non-ephemeral VM (including snapshots!), without the every-machine-has-its-own-kernel overhead.
I could definitely slim things down without disko, virtio, etc, and especially whole separate kernels.. but it's also not such a huge diff that I mind. I'm not adding new services all that fast anymore now that I've got my basics + wishlist set up, so I'll grab another box from the local pc recycler if I ever need space for another ~30 VMs some day rather than when I need space for another ~40-50 LXCs.
And in the meantime if OpenAI publishes a scary brag about how GPT-7 popped a shared kernel on accident I can be relieved that my private bookmarks repo isn't vulnerable while the internet burns down.