A wise man from the east said:
"There's no need to study any Kotlin when you can use an old, kind javascript. The guys from Google spent a lot of time and created another bicycle. Don't want to use it? Lets take Framework7 and quickly and efficiently do what you need (for iOS and Android) without bothering with bugs and without wasting time on purchasing and thoughtful study of books on programming for mobile systems."
This is a joke ;)
Just an example of how good old HTML, CSS and JS save us time and make the world easier and better. And please check app size (about 3 Mb).
Framework7 - is a free and open source framework to develop mobile, desktop or web apps with native look and feel. It is also an indispensable prototyping tool to show working app prototype as soon as possible in case you need to.
https://framework7.io/