This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
寏 combines 宀 (roof) with 奐, but the exact historical development is uncertain. It may relate to an enclosure or surrounding wall, but this is speculative.
The top 宀 suggests a roof or enclosure, and the bottom 奐 looks like a complex structure. Picture a walled compound with a roof, but the exact meaning is unclear.
For カン, imagine a can (カン) being used to mark the boundary of a walled enclosure: can -> カン, and the roof 宀 covers the area.