I dunno — who says you have to focus on one thing? I write all sorts of things: fiction, essays, articles about marketing, brand development, and freelancing.
I’ll say this: pursue what lights you up. Your curiosity will take you where you need to go. I wouldn’t put much credence in a lot of this online advice — much of which isn’t doled out by marketers — about finding a niche, that one thing. If I wrote about ONE thing forever, I’d be bored AF. What these people get so wrong is that there is no one way — there’s only YOUR WAY.
You may find that you like a lot of things that might fall into an umbrella (for me, it’s storytelling and all the forms it can take) and you can take it from there.
:)