Yes, it’s just a matter of copying the RM7 db and media files to your mac. Then update folder setting preferences to align with mac file structures and run ‘fix broken media links’. You can test that on your mac now since your running Big Sur.
Regardless of OS, the same considerations for upgrading from 7 to 8 apply. This is a good reference thread on some db cleanup steps you might want to consider.
Your husband can keep his old windows machine to be able to have a working RM7 version (assuming you won’t want to provide that service ongoing) or he can buy a copy of Crossover or some other sw that will run windows in a virtual machine on his new mac, as Ken suggested. RM8 will run natively on MacOS Monterey and Ventura.
Supported OS versions are here: