Goal: I need to build an internal dashboard using my own database. I don't really need it to be self hosted, I just need it to connect directly to my database.
You can connect your own databases as Retool resources. Here's a link to the doc pages where you can choose your flavor of DB and configure the resource for use in your dashboard: Database connection quickstarts | Retool Docs
It's as easy as providing a connection string in most cases.