vbm: missing metadata. Full Image Restore with .vbk only?

Yes, you should be able to do a restore of just a .vbk using the “extract utility” from the Veeam installation directory:

C:\Program Files\Veeam\Backup and Replication\Backup\Veeam.Backup.Extractor.exe

Follow the User Guide for more info:

https://helpcenter.veeam.com/docs/vbr/userguide/extract_utility_gui.html?ver=13

Hopefuly Support can guide you further if needed. Let us know how it goes.

Best.