It really depends. Tiny pizza roll type things or the small triangles that I’ve seen in Israel are probably Mezonos. But it’s very difficult to say that regular pizza is Mezonos. Those who claim “I’m only eating it as a snack” are most likely giving a cop out. A slice of pizza is a meal. Just because we are spoiled and make ourselves fat and want 1000 calories as a meal doesn’t change the fact that a single slice is a meal.
And recipes, don’t just say “the Halachah is…”. This is a major Machlokes Achronim which has tremendous Nafka Minos. Look at the Ma’amar Mordechai there where he explains the Shittah of the Mechaber.