I know that we can feed all user sessions to an HTTP endpoint as JSON but I don't think it is possible to export a single user session as JSON. If you go to the User Session section in the UI, the details are very in depth so you should be able to determine if a user or a specific session has the correct number of user actions there. Another option is to use the User Session Query to pull the user sessions for a certain application that have a certain number of user actions or above (>=).
Check out the user session query here: https://www.dynatrace.com/support/help/how-to-use-dynatrace/real-user-monitoring/how-to-use-real-use...
You can get session_id value from url - it's last numeric string behing "x" sign.
F.e. if url contains "sessionId=1563360038168x1563360083537x192889524", then session_id should be "192889524".
Or you can check session_id by USQL when you know other parameters like session start time and user id.