Both .qbm and .qbb files come from QuickBooks accounting software, so it's natural to assume that if any kind qbm to qbb conversion is doable, it would be done with this software. Since QBB files are backup files, it's actually more of a backup than file conversion. You can read more about How to work with QuickBooks backup files on Intuit (the developers) website.
Updated: September 26, 2023