You can also improve your App Store Optimisation, write to the editors of the AppStore or publications that can be relevant for a calculator app.
"I wrote some code and made living of it" is only possible if other people are taking care of the rest of the business.
I also wouldn't be too focused on the aspects like "no tracking, no permission, no ads". These are popular topic around tech circles but they are not product but features of a product. Good to have them of course but they don't replace a great product.