As a side note, we _are_ considering adding support for other database backends through Postgres foreign data wrappers: https://wiki.postgresql.org/wiki/Foreign_data_wrappers. If this is something you'd be interested in, please feel free to open an issue on our repo.
If you like Mathesar’s approach but need to work with MySQL, FDWs would let you connect a MySQL database to Mathesar for data entry and querying. This could be useful if you also have Postgres data and want to work with both in a single interface, or if you wanted things like cross-database queries between both DBs.
That said, if you’re only using MySQL, FDWs add an extra layer, and something like VisualDB, since it’s built for multi-database support, would likely be a more natural fit. The main advantage of Mathesar in this scenario would be if you want something open source and self-hosted (VisualDB looks like proprietary SaaS) or if you just like our UI and user experience.