My father used to to work with a nurse who was from the same village as George Michael’s father. I asked him years ago, and he sneered that George Michael doesn’t know what Greek means.
There’s also this:
https://youtube.com/watch?v=jWTsikyE9ns
“Thank you… for thir-… twenty five… years.”
Very halting, and no accent fluency. Comments in the YouTube thread say he did respond to Greek interview questions in English, so likely some passive competence.