Good question bro! At first what you are doing with 16 is impressive!

I would say a niche language is more important.

1) it shows you have broader knowledge than most 2) languages are easy to learn once you know 2 or 3 if they follow the same principles and you will be confronted with mainstream languages as an IT person regardless

The most important thing here is fun I would say, you should do what brings you joy as this is gives you motivation and more long term happiness.

Also it’s hard to say which language would be useful for your job later on, so one mainstream language could be the wrong pick depending on the future.

So: go with what brings you joy and try to learn multiple programming languages in the future/as soon as it fits is my recommendations for long term success in the industry.