I just dump the databases at the same frequency as restic backups, staggered by a few minutes so the dump completes before restic starts.
Dump files are a pain, but the most reasonable way to deal with this is to either set up a quick VM and restore the dump, or if you’re creating separate dumps for each database, restore the dump you’re interested in to a new database on your existing server.
This way, you can browse and use all of the tools that already exist to work with mysql to create an export file of the information you’re looking for, and then import it into your live database.
Trying to add this kind of functionality to restic seems like a lot of work for something that’s easy to work around.