precious, rear, valuable treasure, bullion a jewel
寚 centers on something of great worth: a precious object, valuable treasure, or bullion. The sense of "rear" is likely a rare or archaic extension, possibly related to guarding or storing valuables at the back, but its connection is unclear.
寚 is a rare character. It combines 宀 (roof/building) with 王 (jade/king) and 缶 (jar/pottery), suggesting a container or storehouse for precious items. The exact historical development is uncertain.
Under a roof (宀), a king's jade (王) is stored in a pottery jar (缶) — a precious treasure kept safe.
For ホウ, imagine a precious treasure so valuable it's kept in a special vault, and when you open it you exclaim "Ho!" (ホウ) in awe.