If you fetch a plan with this API: https://app.swaggerhub.com/apis-docs/magicplan/magicplanCloudApi/1.2#/plans/getPlan

You will get a "plan", which contains "plan_detail", which contains "plan" of type PlanData. This type is not documented, and seems to be where most of the interesting things are.

There is a note saying "the current version of this model is in beta. We welcome your valuable feedback and any specific requirements you may have.", but it is hard to have good feedback when there is no documentation – we have to make guesses from the data we get.