prison, horse tender, ostler
圉 centers on confinement and caretaking of horses: a prison or enclosure, and by extension a horse tender or ostler who works within that confined stable space.
圉 combines 囗 (enclosure) with 幸, which here likely represents a phonetic element or a simplified form related to confinement. The character originally referred to a prison or a place for keeping horses, reflecting the dual meanings of imprisonment and horse tending.
An enclosure 囗 with 幸 inside: picture a stable where horses are kept, or a prison cell. The confined space ties together the ideas of a prison and a horse tender's workplace.
For ギョ, imagine a horse tender named Gyo who works inside the enclosure: Gyo -> ギョ, and he tends the horses in the stable.