Log into the device, snmpwalk the device, wait till finished, search for your id with “find” in snmpwalk, log out, snmpwalk device, check same oid for your usename. If you find the oid create a function/probe that generates a notification…
Sounds like it is not supported, maybe try on a couple different operating systems?
If it is a Mikrotik box you could use execute to run the command and return a value. Execute is a pain in the ass but once you get it working it is fine.