NoSQl or SQL?

I’m still continuing C# development but no longer on MonoGame. My needs have now switched to Flutter. If you haven’t come across it, it’s a cross-platform mobile development system from Google and uses their Dart language. This is a modern language originally created back in 2011 as a potential replacement for JavaScript. That didn’t work out as other browser creators (Microsoft, Apple and Opera) didn’t go for it.
So Dart sort of languished until three years ago when Flutter emerged as an alternative to POA (Plain old Android development in Java/Kotlin). Flutter is the UI technology- interestingly it redraws the screen controls at 60 times per second, a bit like MonoGame. But this is no game.
The UI is programmed in Dart and it has one unique feature: You can make a change and see it live in one second. It’s called Hot Reload and compared to the old Compile, redeploy and run cycle is quite amazing., Also Flutter is cross-platform and has controls for iOS that look like Apple native controls.
Now my big decision is whether to use SQL or NoSQL to store data. The data isn’t exactly ordered like a schema, more like each database record has a variable number of name=value pairs. Which certainly suggests something NoSQLish.