This "Before Arrival" was offered as early as last November "Shioyaki mackeral with radish sauce, harusame cyuka, snap peas, carrots, shitake mushrooms, Tawara rice and sesame seeds"
I passed on this meal, so I can't say what it was like.

I can say in November of 2019, United offered specific Japanese meals both to and from Japan. I ordered the Japanese meals on two trips in 2019. They were usually a little better than the standard offerings at that point.