You can check out the following two samples in the arcgis-pro-sdk-community-samples repository to see how you can make Custom pop ups and Layer pop ups:
ArcGIS Desktop SDK Team
Uma Harano, I've looked LayerPopups, but it seems setPopupInfo in FeatureLayer no longer exists at 1.3.
CustomPopup shows how to build a new tool to display a custom popup. I was looking at adding functionnality to the default popup (i.e. the one displayed when users click the map when the Explore tool is active) rather then have users use a seperate tool to trigger the custom identify window with added controls.
The Layer Pop up sample does exactly what you mention - you will be able to customize the default pop-up displayed by the explore tool.
Additionally, the pdf I listed in the previous post explains Layer pop-ups in Pro.
The layer info partly does what I need. I'll start with that.
I think what I found confusing is that I didn't see the Helper directory with the extension methods... my bad.
Thank you for you help.
Additionally, I have listed a video and a powerpoint from Dev Summit 2016 and User Conference 2016 that covered these topics:
We will probably be covering these topics in the Esri Developer Summit 2017 at Palm Springs also