I think that depends on what you're building. If it's something that can work as a website, do that and perhaps throw it in a web view or whatever on your targe

I think that depends on what you're building. If it's something that can work as a website, do that and perhaps throw it in a web view or whatever on your target platforms if you really need mobile exposure. I really like React Native, but it's not the right solution for everything. I've heard Flutter is pretty nice too, so consider your options for cross platform development if it's a good fit for your app. That being said, neither is a very good for for complex apps like games. If I have to make a separate app for both platforms, I'd do whatever I use for my personal device first so I can make sure I can easily test it in real world usage. Once the idea is proven and you have real users, expand to the other platform and step up your marketing game.