Thank you for reaching out to Okta Support, my name is Andrei and I'll be assisting with your question.
There is no functionality in the Okta Admin UI or in the Okta API to achieve the use case. For security purposes, I believe, the option was never implemented.
The only way to achieve this would be to either gain access to the user's credentials or to reset their credentials (in either the Profile Master or Okta itself, based on your use case) and access the user's App Dashboard.
You can suggest the idea for this functionality to be added as a Feature Request, though I it would require a fair bit of "backing" to be implemented, I imagine. You can suggest this on the Okta Community portal by using the 'Feedback' option at the bottom of the Okta admin console.
Technical Support Engineer
Okta Global Customer Care