"Corgi" is a Welsh word - a compound of cor (“dwarf”) and ci (“dog”). The proper plural form is thus "Corgwn" -
"Oh, look, there go Daniel Craig, the Queen, and her two corgwn"- which I believe would be pronounced something like "corgoon."
I list this as "trivia" because the word has been so Anglicized that "corgis" is in common usage, and your use of "corgwn" in a conversation will be seen as pompous intellectualism, unless perhaps you engage your audience by also sharing some of the other English words derived from Welsh (penguin?).
I learned about corgwn from a QI podcast - about which more later after I've finished listening to the lot.