The current optimal approach seems to be writing out a tree to disk like /database/${database}/${table}.sql and then using restic to backup that. Doesn’t take too much scripting, so I’m not sure it would make sense for restic to get into this vs just sharing some wrapper scripts. Just make sure you pass options to your database dumper to maximize de-dupability by removing timestamp comments and forcing consistent ordering, e.g.:
mysqldump ${mysql_args} \
--force \
--single-transaction \
--quick \
--compact \
--extended-insert \
--order-by-primary \
--ignore-table="${1}.sessions"