glare at, look askance at, squint, scrutinizing search
瞟 centers on a sharp, sidelong look: glaring at someone, looking askance, squinting, or making a scrutinizing search with the eyes.
瞟 combines 目 (eye) with 票, which likely contributes the sound and may relate to a flickering or glancing quality. The exact historical development is uncertain.
The eye 目 on the left is paired with 票, which looks like a ticket or a flickering flame. Imagine someone giving you a sidelong glare while holding a ticket, or squinting to scrutinize a small ticket.
For ヒョウ, picture a hyena (ヒョウ) glaring at you sideways: hyena -> ヒョウ, and its sharp, askance look matches the kanji's meaning.