You don't choose your niche - your niche chooses you. When you are worthy enough.

This is the core idea of being yourself and being yourself on the internet. Letting the right audience find you. You don't choose your niche or find it. That will be an external approach.

You create one. By being out there in open. Let people choose you and share your work with other like minded people. That sharing and collection of similar people creates a niche for you.

This is exactly finding your friends.