Whoops, watch the spelling! "The flog prince" and "the frog prince" have very different meanings! In this context, "what" means "things that..." "What" is used as an object here, not a question-word.

what is ”それだけ”　みたいな　いみです　:)

Right, it is used as an object word. It increases the flow of the sentence. You could say "...and only liked things that looked pretty and things that tasted good." which sounds less elegant, in my opinion. 「美しい物とおいしい物しか好きじゃなかった」と同じの意味だと思います。