I haven't looked into it. But I suspect that if Linux phones can get Kotlin to run natively, we'll start seeing some of the apps from F-Droid ported over and that will be the turning point.
I'm not sure what "the Linux community" really means but I would bet that pure open source Android based on AOSP are more popular than the non-Android Linux mobile OS combined.
Kotlin targets the JVM right? I think you'd need either a port of the runtime (dalvik?) Or an api translation later a la WINE.
But I don't actually know anything, so don't listen to me. Having a fully Foss phone with support for the android app ecosystem would be wonderful though