At this time we only have the Improvements data available through the API, they team are starting to work on the Process data, and making some of this available, however there is no timeline set for this yet.
The Promapp user community has been asking for this since before Nintex bought Promapp and it was implied that it would be delivered soon after the transition - with more devs, more capacity to enhance the product, etc.
Back when there were in-person Promapp Connect conferences it was on the agenda every single year as far back as I can remember (2017?). It's been one of our greatest frustrations with Promapp. ☹️
Just reading the other feedback to this. Yes we have been waiting for the repoting APIs for a number of years... I notice in the that work is being undertaken on feedback which I wouldnt have thought was a high priority? It would be great if we could get an idea as it if this is going to be delivered at all?