Medium is an easy place to have many varied interests — there is an audience for everything. Why do you feel you’d have to pick a niche for blogging/Medium?
You can write anything you want and tag it with anything! Don’t feel hemmed in, it’s your blog, write whatever you want.
While I write a lot about writing, entrepreneurship, and marketing, I also write about whatever I want, including American Ninja Warrior, Shane Dawson, poems, etc.
Just jump in, you’ll love it.