This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鐎 combines 金 (metal) with 焦, which likely contributes the sound. The exact historical development is uncertain.
The left side is metal 金, and the right side 焦 suggests scorching or burning. Picture a metal pot or vessel used over fire, which fits the kun reading なべ (pot).
For ショウ, imagine a metal pot being shown off at a market: show -> ショウ, and the metal pot is the center of attention.