EMV chip & pin cards have always been capable of offline payments.
In the UK this has definitely worked in the past - I remember many years ago there being occasions when something was wrong with the network connection(?) at my local supermarket, but still being able to make a payment in offline mode. This works because the payment terminal authenticates the PIN directly with the chip on the card. They just can't check your balance is sufficient to pay for what you're purchasing.
TfL also accepts your contactless card in offline mode: their buses operate in tunnels and other areas with a poor mobile data signal, but cards are still accepted at all times.
In the UK this has definitely worked in the past - I remember many years ago there being occasions when something was wrong with the network connection(?) at my local supermarket, but still being able to make a payment in offline mode. This works because the payment terminal authenticates the PIN directly with the chip on the card. They just can't check your balance is sufficient to pay for what you're purchasing.
TfL also accepts your contactless card in offline mode: their buses operate in tunnels and other areas with a poor mobile data signal, but cards are still accepted at all times.