Interviewing: Mobile System Design Resources

I've had two interviews recently (Microsoft and Twitch) where I've been asked to design different mobile system components. Microsoft: "Design a generic chat interface SDK" Twitch: "Design a generic analytics SDK" I feel like these are mostly job specific skills that you either have experience with or you don't, but are there any resources for answering these questions better? For example, I think this is a great resource for backend and front end web developers and I wonder if there might be something someone suggests for Mobile Developers: https://www.educative.io/collection/5668639101419520/5649050225344512

Grokking the System Design Interview

Educative: Interactive Courses for Software Developers