They behave as something between an object constructor and update function, and they're basically always nouns

In the Kotlin Coding Conventions there is a exception for factory functions. Do the Compose functions act like factory functions?

Yes, but in a rather special way since you don't get a reference to a backing object, and the system can choose to reuse/update an existing composable during a recomposition

In other words the Compose functions are similar enough to factory functions that the Camel Case convention makes sense.

yep

That should be mentioned in the JetPack Compose FAQ.