My mental model is to think of a relational database as an amazing Swiss Army Knife. It can do anything I might need to do, but it's not awesome at anyone thing

My mental model is to think of a relational database as an amazing Swiss Army Knife. It can do anything I might need to do, but it's not awesome at anyone thing. I can cut a branch with a Swiss Army Knife, but it's much harder to open a can with a chainsaw. Unless you are 100% certain what problem you are solving take the Swiss Army Knife. Swing up multiple specialized tools or trying to make them do things they weren't designed for will just cost you time that you aren't spending on finding product-market-fit and then it won't matter if your solution won't scale to millions of users.