In that case, and since you are looking for suggestion on where you can do work most or fast or most productive for a single developer, you could consider an alternative to learning a framework.

Learn a platform. Not a framework.

You could pick at platform to specialize on and learn whatever framework / language you can use to extend that platform.

For example you will be very productive very fast if you pick a platform like Microsoft Power Apps[1]. Although it is a no/low code platform there are tons of places to write code especially when you start to leverage azure functions. (c#/javascript/phyton/java) There are alternatives to Power Apps but that's the platform I am familiar with.

I know its fun to build apps from scratch but if you want to be productive fast you can cut a huge corner by building on top of an existing app platform.

[1] What is Power Apps? https://learn.microsoft.com/en-us/power-apps/powerapps-overv...