There are actually plenty of sub communities on Steemit, the hardest part is finding them.  You are correct in saying that the majority of our feeds are probably filled up with crypto stories.  Those are still a big deal right now and they probably aren't going away.  Especially since Steemit is built on the STEEM blockchain.

I have said this as answer in a lot of my posts, but it really is what I believe is the most helpful.  Get a Discord account.  I feel like that should be the second most important thing you do after you get your Steemit account.  

Once you are on Discord and you start joining some of the servers, you will start to meet people that share the same niche interests as you.  From there you can build the community that you want.  It can be a huge thing.

I am a fan of alternative music.  A person I met on Discord is also a fan of alternative music.  He started a challenge that has people posting their favorite alternative bands on the weekend.  It has come to be a huge following that many people are posting to now.  The Metalweekend tag is another example of a person that had a passion for a specific topic and turned it into something huge.

That would be my second piece of advice.  Besides creating a Discord account and meeting people on there, try to turn the topic into a challenge or even a contest.  As you start to get people responding to it, you will then make those connections with the group of people that you want to target and read from in the future. 

It doesn't happen overnight, but if you put a little time, effort, and thought into it, you can build that niche community that you are looking for.

Good luck!