When I need to make a POC about why it is dangerous to let the session unlocked, I used to put a mimikatz on an USB key and get the logon credentials in clear text. But sometimes the client has no debug privilege so mimikatz cannot run.
But, when I use meterpreter (for example through psexec with a domain user creds (not privileged)), I can really easily obtain SYSTEM privilege by using the lazy getsystem command. So, I guess there are well automated privilege escalation exploits that I can use from my USB key locally plugged to the victim session (unlocked).
I have seen that it is easy to generate meterpreter instance with msfvenom, but all the possibilities I see are about reverse shell (aka shell over network: reverse_http, reverse_tcp, etc.).
For my problem I just need a standalone local executable: just put it on my USB key and execute it locally.
This sound easy but I don't see any example of how to do that. I guess I could create a local reverse shell and execute it on the victim PC and then connect to it from my machine but create a local meterpreter should be easier.