Don't forget about the 'ATTACH DATABASE' option as well. It is great for linking up individual SQLite databases when you need to do a broad-based query across multiple sources.

https://www.sqlite.org/lang_attach.html

If you use a GUI front-end like SQLiteStudio (https://sqlitestudio.pl/), attaching databases is ridiculously easy to do. Just add the database name from the left column in front of the table or table.column label for the database you want to reference. Most SQLite GUI's will do the attach command for you internally.

I add the database name to my queries instinctively now in SQLiteStudio, so that no matter which DB is currently in focus/opened the query runs on the one I intended it to run on.

You might also be interested in https://github.com/src-d/go-mysql-server , a Go library for putting a MySQL-compatible frontend over a custom virtual data source.