Button in Nintex Mobile
I think a button in Nintex Mobile would be good.
1. go to next step (like a questionnaire)
2. trigger warning message
3. trigger an action
Thank-you for presenting this idea to us. We currently don't offer this feature in Nintex Mobile however I believe that you should be able to do this using Nintex App Studio which allows you inject custom HTML into the app.
This post by Dan Stoll explains how to do so: