Depends on how complex you want this to be. You could send out an Adaptive Card or Email to the user with a hyperlink to the item, have them click the link and do their work there, then go back to the email or adaptive card and interact with it to close the Flow.
Alternately, you could build a sharepoint list for tracking. Have two Flows, the first to check for approvals needed and send out the notice to the user, make a List entry to say the notice was sent, then the second flow triggers on item update and checks against the List to see if a notice was sent on that item and if the item was successfully completed, then sends a notice that the approval is complete.
