Dave Leeds is a US Kotlin developer and educator focused on the Kotlin language at depth — particularly the concurrency and coroutines model that makes Kotlin distinctive among modern JVM languages.
His CourseFlix listing carries Kotlin Coroutines and Concurrency — a focused treatment of Kotlin's coroutine model, structured concurrency, the dispatcher landscape, flow / channels, and the patterns for writing safe concurrent Kotlin code.
Material is paid and aimed at Kotlin developers building concurrent applications, particularly on the Android and server-side Kotlin tracks. For broader content, see CourseFlix's Mobile Apps Development category page.