Haven't picked any specific one for full time learning. Thats why i am asking.
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...
If you aren't familiar with elastic stack don't let it put you off that they mark it as search product [2]. It has a tons of integrations [3] [4] allowing you to connect with almost anything and write code against it using any framework. Elastic is awesome.
Elastic Stack is much more code heavy than an low code platform but you get tons of features out of the box.
In the eyes of you app elastic is just an API that provides access to your data. When evaluating elastic try to abstract from that it is a search engine. Try to think of it as just a mechanism to access and work with data. Instead of firing a sql query against a database to get your data, you execute a search query.
From that build app app just like any other data drive app using whatever framework or language you prefer.
[1] https://www.elastic.co/elastic-stack/
[2] Elastic Search is the search component in the elastic platform. Elastic Stack is the platform.