Yeah. I agree, I saw the SaaS-style pricing for running on my own infra and couldn't see any reason why I'd want this. I also don't see the technical upside to SlicerVM. It feels very risky given I've never heard of anyone actually running this in production. I think I'd take my chances with Proxmox plus microVM add-ons first.
Author of a free open source alternative to slicer, based on a fork of libkrun (not firecracker based) that runs locally across wsl, macOS, and Linux natively.