Let me explain my situation before people start giving their opinions. I am a seasoned web developer, hence I have a great deal of experience working with web frameworks as well, like react. Recently I tried out react-native, and I really enjoyed it. But then I heard about Flutter, and it looks promising. Now I am also tempted to learn Kotlin ( Android ) development. The thing here is, web is a platform that is so flexible that it will beat the shit out of Native development in the near future. On top of that, learning the Android native architecture and style of coding will be like learning everything from ground zero. I am not sure should I just stick to Flutter or should I instead try out android development.
In short;
Now keeping the above points in mind, give me some nice, "to the point" opinion/advice.
Well. When creating an app, it is important to decide on the technology based on the type of app you want to create.
At least for now, hybrid apps (created with web tech) are usually a lot less performant than native apps, however web technology is useful for UI development. So, if you have to create a UI-heavy app which does not need to calculate a lot of stuff, hybrid apps are the better fit. For example, if you create a news-app or chat app, hybrid code will get the job done and is cross-platform.
This implication also means that if you have an app which has a lot of calculations and requires lots of performance, a native app is the better choice. For example if you plan to create a game or AR app, native will deliver better performance. The downside is that you often have to deal with a UI system, which is inferior to HTML/CSS.
However, technology is changing a lot! We have different developments, which are still a bit hard to use, now, but will open up entirely new decision making later on. I am talking about WASM! Write your code in C/C++, Rust or any other language supporting WASM as a compiler target. WASM will deliver very good performance for hot paths, making performance-hungry hybrid apps an option. I'd say go for that if you have a lot of UI, but also need performance in some places.
By the way! Many languages, Kotlin included, cannot just create binaries for a single platform, but compile to many platforms from a single codebase. For example there is Kotlin/Native, which can be used to compile to iOS as well. I just don't know how big of an effort that is.