dried rice, dry provisions
糇 centers on preserved grain food: dried rice or dry provisions prepared for storage or travel.
糇 combines 米 (rice) with 侯, which likely contributes the sound. The character is associated with dried grain provisions, but the detailed historical development is uncertain.
The left side is 米 (rice), and the right side 侯 looks like a container or a person. Picture rice being dried and packed into a container as provisions for a journey.
For コウ, imagine a traveler packing dried rice into a coat pocket: coat -> コウ, and the rice becomes dry provisions.