Former Brit, can confirm. My American wife thought it odd to see people eat pizza with a knife and fork when we lived there.
My husband has a sort of famous relative who’s pretty uppity. He went to dinner with her, years ago, at a fancy restaurant, and he committed the faux pas of cutting into his fish with the side of his fork, and she nearly slayed him with a wilting look, making him feel foolish and out of place. He knew better, but he just wasn’t thinking. Manners are nice, but it would have perhaps been more gracious, and therefore more proper, if she had either ignored his mistake, or picked up her fork and copied him. (I eat pizza with a knife and fork until it cools off enough to handle. It tastes good, either way).