to eat too much, surfeited, to confer
饇 centers on excess in consumption or giving: eating too much to the point of surfeit, or conferring something in abundance. The two senses are loosely connected by the idea of overflowing beyond normal limits.
饇 combines 飠 (food) with 區, which likely contributes a phonetic element. The exact historical development is uncertain, but the structure suggests a phono-semantic compound related to eating or abundance.
The left side 飠 is food, and the right side 區 looks like a container with many compartments. Imagine a person eating from every compartment until they are completely surfeited.
For ヨ, picture someone so full they can only say 'yo' in a weak voice after eating too much: yo -> ヨ.