This might not be responsive because spare time isn't something I can count on filling with other than sleep. If you don't mind a more general response, what I do is keep a list and when the next paying project comes along I'll try to use something off the list to realize the product. As a ferinstance, right now I have Elixir, Rust and FreeRTOS on the list. Two days ago a project came down from on high where even though I can't demonstrate that I need an o/s (it's not internetworked) I'll implement over freertos and get that off of my list.

Often I discover a problem in my everyday life. Last time i did not find a tool to rename and transfer files, that fitted my needs (on Windows!!), so i did some research, what language would be the right tool for the job. Thats how i learned golang.

The most important things for me, learning a technology are:

- Having fun, learning it

- Solve a concrete problem in my life

- First success in a short time (<= 1 week)

- It should improve my skills in general

- Best case: It is something i never did before or it improves something, i already did

Currently I'm learning Rust, to improve my copy tool written in golang ;)

I think you should lengthily think about WHY you are interested in x,y,z. Formulate it by jotting it down. It should make what is a priority clearer.