Ubiq; did rav belsky tell you specifically a “side dish”? In yeshiva everyone quoted him as saying “2 slices and even a bite/ma shehu more” would require hamotzi – he wasn’t completely convinced of it in any case, as he told me directly to follow the minhag ha’olam.
He also was wont to say that apple juice makes no difference in the status of dough, and that shu”a is discussing thick juices which make a very significant change in taste and other characteristics of the bread. He said even if the dough had 3/4 apple juice and 1/4 water it would still be hamotzi; he repeatedly told us that mezonos bread is a contradiction in terms, and did not accept any of the marketed mezonos breads as being such.
The phb”k status of pizza stems from its filling, according to rav belsky.