pant, many
嘽 centers on heavy breathing from exertion or excitement: panting. The sense of 'many' likely extends from the idea of a crowd breathing heavily together, but the connection is loose and the kanji is rare.
嘽 combines 口 (mouth) with 單, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound related to breath or voice.
A mouth 口 beside 單 (which resembles a simple net or single unit) can be imagined as many mouths panting together, like a crowd gasping for air.
For タン, picture a tan-colored dog panting heavily with its mouth open: tan -> タン, and the dog's panting matches the kanji's meaning.