It depends on the product. Sometimes you can test the market without building anything, sometimes you just need a landing page, and sometimes you need to build

It depends on the product. Sometimes you can test the market without building anything, sometimes you just need a landing page, and sometimes you need to build an app. Sometimes you can build the app with no-code tools, sometimes you can use a platform, sometimes you need to hire an agency or get a technical co-founder. Feel free to email me if you want advice for what you have in mind. My email is in my profile.