We already have a column called album_id, which is primarily used to separate albums in the models. Currently this is not in use for local files, only Tidal and Qobuz. So basically all you need to do is to update the tagreader code to read the musicbrainz id's:
https://github.com/strawberrymusicplayer/strawberry/blob/master/ext/libstrawberry-tagreader/tagreader.cpp