How would I be able to check something like this myself with my own node?
Are you periodically retrieving the data from peers.dat or are you using a better method? If it's the former, then I'll parse the peers.dat later on at fixed intervals and see what I can find.
I think it's the same as the the result of
getnodeaddresses 0 RPC.
Note: it will take a while (
GUI will freeze while loading) if you have hundred of thousands of entries in your peers database.