I'm not sure if there is something useful for your situation in https://github.com/Kotlin/kotlinx-atomicfu. I haven't used it directly yet. I've only seen it as transitive dependency in my projects so far.
But that's more like
I don't think atomicfu has collections, just locks and atomics, although I could be wrong. We implemented a very basic set of concurrently collection here: https://github.com/touchlab/Stately/, module
stately-concurrent-collections
. I assume something more comprehensive will be released at some point by somebody, but haven't heard of anything yet.