Have learned a bit of bash but that's what has kept me going on always. There's no point in learning million little inconsistencies all of which aren't even documented anywhere like a MDN or MSDN if you will.
https://gist.github.com/nicerobot/53cee11ee0abbdc997661e65b3...
But you don't really need to spend any time learning them, just plug shellcheck itself into your editor and go write some scripts. I've written don't know how many thousands of lines of bash (and sh, depending on the task at hand) that work across five operating systems, and it's honestly a non-issue if you follow the warnings.
The reason to learn it is that it can make your dev experience better. Make falls into this category as well. Both are great ways to combine multiple tools together.
That being said, I'm using more Dagger for this purpose these days, which provides you SDKs for your fav langs.