This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
昮 is a rare character whose historical development is uncertain. It visually combines 日 (sun) and 功 (achievement), but the original meaning and component relationship are unclear.
The sun 日 shines over achievement 功, but the overall meaning is unclear. Imagine a rare character whose meaning is lost in time.
For ショウ, picture the sun 日 shining (ショウ) over a great achievement 功: the sun's show (ショウ) of light highlights the work below.
—