This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 粇 is uncertain. It combines 米 (rice) with 亢, but the original semantic and phonetic roles are unclear.
The left side is rice 米, and the right side 亢 looks like a person with a high neck. Picture rice grains stuck in a tall, narrow container, but the overall meaning remains unclear.
For コウ, imagine a cook (コウ) inspecting the rice 米 on the left, while the right side 亢 looks like a tall pot. The cook's sound cues コウ.