Flutter and React Native as are great for small apps that don't do much but work on both iOS and Android. Kotlin is great for native performance on Android with large apps that require some processing power.  

 What is Amethyst done with?  

 Kotlin Native with the Jetpack Compose UI toolkit. 

 I don’t do app dev, but do you really need something as heavy / complex as React Native to build “small apps that don’t do much” ?? 

 I thought you were gonna say 
"I don't always do mobile, but when I do, I burn the shit out of Java". 

 LOL

I’m a data/analytics engineer, so it’s mostly Python & SQL for me, and a ton of dbt tempting in a data warehouse env.

I did start learning Go recently, and I know enough JS and HTML to build a really shitty website.

Everything I know about React is the exact opposite of “simple” or “lightweight” 😂.  But I don’t know much about React Native. 

 If it's only android kotlin is better.
If eventually you need an iOS app then use flutter.
Kotlin you get you a better performance if you need to do something heavy.
Flutter works for apps that don't need much processing power.
In my work I have a flutter app with 200+ screens but the app only do get, post, delete requests and take some pictures.
If you need some background processing, notifications and other stuff using kotlin is a lot better 

 RN is easy if you writed js before. 

 Thank you all for this. 

My issue is that I already know a bit of flutter but find it clunky and never really liked it. Also, the rumours are that Google has abandoned it and the flutter team is a little adrift. 

React may be a tested and proven way to get something done and the ecosystem seems capable to solve any problem. 
Kotlin is a whole different ball game, because it locks me to android (has is pros and cons) but ultimately if the aim is to release my own products, kotlin seems like and overkill for now. 

If what I need to to prototype faster, flutter is too clunky and hard and has a bad outlook. React seems like the sensible option.

Agree?  

 I always thought React was better than Flutter. But it is also a bit slower. But it's def. great for prototypes.