I’ve done something extremely similar with a custom NixOS iso for my docker VMs to make versioning and backups easier (golden image live disk with SSH+Docker+Dockge shared between all VMs + local persistent storage specific to each VM).
You can configure frigate via OCI container with custom config, as well as NFS mounts, SSH server, etc and then have a read-only live disk that boots up, mounts NFS share, and then starts up frigate.
https://git.mlaga97.space/mlaga97/persistent-live-docker-flake has a builder for a live disk that will mount /dev/sda as ext4 to /persistent, and then start up dockge and whatever containers are present from the previous boot automagically.
OCI as in Open Container Initiative.