This seems like it would only work if the applications in question didn't contain any PII - as soon as you get into applications or flows within an application

This seems like it would only work if the applications in question didn't contain any PII - as soon as you get into applications or flows within an application that contain some form of PII, either displayed or the user entering it, having them send a screenshot of the entire screen is asking for the user to accidentally leak their PII to the person reviewing the ticket. Where I work (in which the above would be a problem), we make sure to log enough information that given a relative timeframe of when the user had the issue, we can usually narrow down to where the issue was using context and some querying of the logs (splunk is incredibly helpful for this)