Best practice for managing sub{U.G}ids for sysusers.d

[djarbz]

My understanding is that we should use sysusers.d to manage users defined in the image.
I would like to run Podman containers as rootless users defined in sysusers.d.
Unfortunately, /etc/subuid and /etc/subgid is not populated for sysusers.

What is the best practice to populate these when using bootc?
Or is there a better method than using sysusers?