I'd like to suggest that the controls made available in the app be refreshed for a more modern mobile look. Currently PowerApps has a number of mobile friendly controls that are very useful that I believe Nintex Forms for Mobile would benefit from. In particular;
-a slider control for values between a Min and Max amount
-a timer control that allows you to perform an action on the form after a certain amount of time has passed
-ratings that give the user a nice visual way of giving something a rating in the app
-PDF viewer allows PDF's to be rendered inside the app, useful for agreements etc.