Or am I now able to transfer objects between threads? Often times I might want to do several things in the background on a single worker involving several dependencies? Is something like that possible with this threading model?

Yes, you can transfer objects between workers. We try to avoid notion of thread, as it is misleading, but workers are executed on top of OS threads.

Is there a 1-1 mapping between a worker and an OS thread?

Not 1:1, not for every thread there's worker, but for every worker ther is a thread

So workers don't share threads?

Sure, the whole idea beyond workers is computations offload, if you want to share threads - coroutines are way to go.

Can you recommend a sample of kotlin-native coroutines that offload work to background threads?