See how sucessfull Kotlin/JS and Kotlin/Native are on the wild.
The same libraries that can be used from Kotlin?
The toolchain in both cases is basically IntelliJ (rebranded as Adroid Studio)
At that point one could also say "why Anrdoid?".
Now if you plan to dynamically link to Java libraries that require JVM opcodes without counterparts on DEX, SIMD, Panama, Java Standard Library post Java 11, then thought luck.
See it as an opportunity to learn how to use the NDK (for SIMD), or write your own Kotlin versions.
Kotlin was designed to replace Java 1.6 and that's about all it's good for.
Not sure what K was designed for. But we use it to fix J's billion dollar "implicit nulls" mistake, and terse syntax (making it useful for templating: Kotlinx.html), and pass-as-value method references. We love it's hang towards immutability.
K is not Haskell, but it sure feels a lot safer that J (where a lot of strings were used to refer to methods, and strings+Groovy was used to do templates).
Bottom line: I'm too old --and life's too short-- for NPEs.
I moved from Java to Node (then Typescript) about 8 years ago. Moving to a language that doesn't allow implicit nulls makes a world of difference, importantly, at "programmer" time, not just build time.
That is, when programming in VSCode, I immediately get feedback if I attempt to use a nullable variable in an unsafe manner. That has huge productivity benefits compared to if I only got that feedback after my build ran.
Similarly, simple things like safe optional chaining (i.e. foo?.bar?.baz) makes code so much faster and easier to write, and AFAIK this hasn't been added to Java yet (correct me if I'm wrong).