Hey, I reckon with Flutter, Firebase, or Superbase you're looking at the right technologies, though I wonder if there's a faster way to get your new app up and running.

Your first sentence "CRUD SaaS" app made me wonder whether a low-code solution could do the trick for you. How much UI customization are you looking for? Is this a typical "admin panel" web app with a couple of screens for login/logoff, data entry, etc? Or is this something with a highly customized UI? And do you need native mobile or just a responsive web app?

There are a couple of online database builders that give you a hosted relational database, authentication, the ability to write logic, and deployment in one platform.

Our company Five, for example, has a low-code IDE that gives you a fully-provisioned MySQL DB, a prebuilt responsive React/MUI user interface, and one-click deployment of web apps onto AWS infrastructure.

You can build most of your application using Five's pre-built features. But you can also write SQL, JS or TS to query your data, or to add logic.