give pleasure, be pleased, happy
衎 centers on a state of joyful satisfaction: giving pleasure, being pleased, or feeling happy.
衎 combines 行 (to go, action) with 干 (shield, stem), but the exact historical development of how these components express pleasure is uncertain.
Imagine a person going (行) out with a shield (干) raised in victory, feeling happy and pleased after a successful battle.
For カン, picture a can of your favorite drink giving you pleasure: can -> カン, and the happy feeling spreads as you go about your day.