I'm currently trying to create an app which has offline functionality, similar to Collector. That is, the user can go to their Gallery on the device (eg an iPad) and, if the map is able to be used offline, the user can select an area and create the downloaded package directly on their device, and sync it up as they go.
Is this possible? At the moment everything I can see points to having to create and package it up using ArcGIS Pro.
We support a lot of users who operate out of areas where they have no connection in the field, in different timezones and sometimes with emergency situations who can't wait for me to be online and packaging maps up and then them having to download them again, then doing it again if it's wrong. Much better if they can do it themselves just using the app.
Yes, it is possible with AppStudio as @GISJot mentioned above. I also want to point out that AppStudio MapViewer template supports the offline workflow you mentioned, you just need to set up the Webmap with pre-planned offline map areas from ArcGIS Online. Then, you would be able to download those pre-planned offline map areas in MapViewer template.