wind, walk out of straight path
迤 centers on deviating from a straight course: winding, meandering, or walking out of a direct path.
迤 combines the movement radical 辶 with 㐌, which likely contributes a phonetic element. The exact historical development is uncertain.
The movement radical 辶 suggests walking, and the inner part 㐌 looks like a winding path. Picture a road that curves away from a straight line.
For イ, imagine an easy winding path that curves gently: easy -> イ, and the path winds without effort.