Misago required postgresql as it database backend. But I think support sqlite3 in development environment is more convenient for developer.
For developer convenience we are providing Docker config that will install and setup PostgreSQL database (as well as all other dependencies) without polluting it to your system.
When you are using database specific features, using different database in production and different in development doesn't make any sense. You would have to somehow disable those features for users with Sqlite, but that would take previous extra work that is better put elsewhere 😉