[pjc50]

Obvious dependencies: you need a computer of the relevant type if you're going to go native.

Are you going to sell it as a product? How? Mac store, Windows store, online from your own website, Steam, something else?

How are you going to acquire customers?

What apps are you competing with (hint: there's a lot, on all platforms)?

Which native platform are you most familiar with/want to become familiar with? (Note that Windows has several platforms within it; UWP is the obvious modern choice, but maybe you want a WinForms app)