This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
饛 combines 飠 (food) with 蒙, which likely contributes the sound. The exact historical development is uncertain.
With no clear meaning, picture a mysterious dish covered by a cloth (蒙 can suggest covering) and served on a food tray (飠). The covered dish represents something unknown.
For ボウ, imagine a bowl (ボウ) of mysterious food covered by a cloth: bowl -> ボウ, and the covered dish hints at the unknown meaning.