what capabilities are missing when viewing a Dashboard in a web browser that's prompting you for a mobile app?
Well nothing to be honest in this regards. When I browse and access the dashboard via AGOL it looks good, thanks to your guidance. The capabilities and functionality is as advertised. I would assume the app has same capabilities, not sure of the complexity behind all the mobile app tech.
Can you please share requirements/use case?
For me it's the ability for my end users to have the same experience as far Explorer, Survey123, Collector apps. The ability to tap an app and have that access to that specific feature be it a general web map, survey or editable web map is invaluable to end users in my opinion. Easy and understandable. The dashboards fall into this category. I would want my executive mgmt, stakeholders and field personnel to have that experience versus browsing, signing into AGOL. I suppose i could just add a shortcut to their individual phones but seems out of line with the ESRI app ecosystem. Burdensome if the url changes and\or multiple dashboards become requested.