So, I plan on creating a game using packp3d so I can let people launch it on my website. I’ve seen a few things like Toontown House a long time ago where they accessed databases with a .p3d on their website so they could open accounts, get data, etc. Is this done in MySQL or SQLite or what? And are there any examples anywhere?
.p3d running in browser is same as standalone game. So it is up to you what you will use. I recommend PostgreSQL for database.
The kind of database you use will depend on you needs. If you want/need database on a client, or working on prototyping, then I suggest using a flatfile database like sqlite. The advantage here is that you don’t need an sql server program to use SQLite.
MariaSQL, Postgres, even the nosql versions like mongodb require a separate server program.
You might also want to consider using python database middleware like sqlalchemy sqlalchemy.org/