I saw this was a Django app so I dug around to look at their models. As far as I can tell this is all they have: https://github.com/tubearchivist/tubearchivist/blob/master/t... - just a `Account` model.
It looks like Django + SQLite is used for user accounts, but all other data storage happens in Elasticsearch.
It's an interesting design decision. I would have gone all-in on the database, and used SQLite FTS in place of Elasticsearch for simplicity, but that's my own personal favourite stack. Not saying their design is bad, just different.