Beginner's question: how to interact with outside world from compose, lets say I have on click on a button and lets say that I want to start a service with that. Or the other way around, I get a message from service in a an activity holding composable, do I need to pass it to viewmodel and trigger recomposition via live data for example or do I have some other options?

Depends on your architecture, but compose event handlers for things like button click are just functions. You can use them to invoke methods on your view model and then have your view model do side effects, or bubble it up your architecture further.

@Nemanja Mladenović in case you missed, here's a related video

I have seen it, but still wanted to check what is required to interact with outside world even if answer was kind of obvious