Currently setting this up on my own repo:
https://github.com/Venefilyn/cockpit-bootc/tree/feat/vm-setup
I was met with issues regarding bootc as cockpit.socket doesn't work in bots/vm-run -s cockpit.socket centos-9-bootc due to the bootc/ostree nature of the image.
We have a solution to this in the ways of podman container runlabel that can install a systemd service. This service is also not cockpit.socket so needs to be bots/vm-run -s cockpit.service centos-9-bootc