Make the license BSSL (or AGPL, or whatever you want), and if you don’t already have it get out there and make your “fuck you” money, because that idea seems like almost a sure thing!

Having to so none of the marketing and just showing up on “firebase pricing” or “firebase cheaper” searches or whatever feels like a slam dunk, and since you’ve picked postgres you’ll probably have a nice well trodden path to reliability and perf