Does a Seedvault Backup only include data from a specific profile, and could I restore from a Owner profile backup in another profile on another device (or even on the same device) or vice-versa?

    Seedvault backups are per profile.

    Andromxda could I restore from a Owner profile backup in another profile on another device (or even on the same device) or vice-versa?

    Likely but I'm not sure. Remember to always try Seedvault backups to verify that they work before you depend on them. They can be really unreliable sometimes.