Product management course
The system design course so far is very comprehensive. The advantage that you get during the mocks with senior resources is that you understand how to tackle the product questions at senior rounds(not just execution based but those on vision, company strategy and behavioral much better). These questions are generally asked and a candidate is grilled in deep for senior roles. Besides using the course just for interviews the depth of the content and the detailed explanation puts you in a position where you start understanding most of the regular architectures pretty easily in day to day work. Since this is a very important skillset for platform product managers i would strongly recommend the course for any aspiring Technical PM.