Unless @comtech’s solution works for you, I can’t think of a way that would be simple. Also, you’re actually going to have to drag through the ASTDB because some of your extensions may be logging in instead of being “assigned”, which (I’m reasonably sure) is all you’re going to get from the MySQL database.
Thank you all for your responses. In our FreePBX environment, checking these manually isn’t a huge hassle, just wanted to ensure I wasn’t missing an option that would have saved time when the need arose to review the ring groups and queues. The Asterisk queue info page lgaetz mentioned will definitely help.