Do looked and balloon have the same vowel sound?

No, "looked" and "balloon" do not have the same vowel sound.

* Looked: The vowel sound in "looked" is a short "u" sound, similar to the vowel sound in "book" or "push".

* Balloon: The vowel sound in "balloon" is a long "oo" sound, similar to the vowel sound in "moon" or "food".