round, go around
圜 centers on circularity and cyclical motion: something round, or the act of going around in a circle.
圜 combines the enclosure 囗 (surrounding boundary) with 睘, which likely contributes the sound and the idea of circular motion. The character is associated with roundness and encircling.
The outer 囗 is a circular boundary, and inside it 睘 looks like a complex round object or a path that goes around. Together they suggest something round or the act of going around.
For カン, imagine a can rolling around inside a circular enclosure: can -> カン, and the can goes around and around.