The Compose dev challenges have mockups and all the assets you'd need to make them. There are three different apps. I think it's probably along the lines of what you're looking for.
Chris Sinco [G]
11/22/2021, 11:30 PM
You could also find the View based implementations of the Material studies and redo them in Compose
But I would +1 again to using the Compose Dev Challenges for learning - we specifically designed them so that one should be able to finish each from start to finish in roughly 3-5 hours, which ended up panning out in reality when we ran the challenges. If you need a challenge, I'd try to implement all three as they are different designs and have unique aspects to each. And we include all the design assets/specs: https://github.com/android/android-dev-challenge-compose
We actually use them internally to help new team members onboard to Compose