Hi thankfully better offline management and access is in the pipeline and should hopefully come out of the works soon (my hope).
In the meantime the Bitwarden API might be something too look into if you are familiar with and feel comfortable putting together something that could utilize the API.
The Bitwarden CLI will also play into this and scripts can be set up to export organization items for backup, and I’m sure secondary scripts could be used for importing to an on-prem Org as a hotspare.