[EdwardDiego]

I haven't used Kotlin on Android, but on the server side, it does make some of the boring stuff easier if you're stuck on an old JDK - e.g., Jackson supports serialising/deserialising straight into Kotlin data classes, you don't need this if you can use Java 14+'s records, but if you're still on Java 8, it's far nicer than all the boilerplate POJOs.

As for the DB layer, I quite like JDBI which integrates well with Kotlin also: https://jdbi.org/#_kotlin

I'm not familiar with RxAndroidBLE, but they have some Kotlin examples on GH: https://github.com/Polidea/RxAndroidBle/blob/master/sample-k...