End Point Verification Helper App

So I have been going round and round in circles trying to understand how the Helper App works and triggers for End Point Verification and official documentation aswell as Gemini seem to say that in order for the Helper App to trigger a prompt for an end user to install it, you first need a rule in place that requires the visibility of signals only the helper app can see. 

I have been trying AV requirements in  rules etc but nothing seems to trigger the Helper installation. 

For context, this is required for BYOD extensions and so deploying the app is not possible.