Is there any way to get certain stockpiles to feed other stockpiles? I posted this in the general before I saw this link here.

Not with current programming. A few folks have asked about this. I may consider adding it at some point. It would require a rewrite of a bunch of logic.
For now the best way is to use a transport with a route.

I know what I'D love to see, but I dunno if it'd be doable... basically, some way to prioritize one material over others, ideally affecting both drones and shuttles - but frankly, even if it's just the shuttles, I'd be grateful. I've had repeated problems with food-shortages and starvation due to available food-supplies failing to reach outlying domes, because the shuttles were busying themselves with transporting everything ELSE. Setting individual building prioritizers is pretty laborious, and I'm not sure if it affects the shuttles regardless...

(I've also had colonists starve to death while a rocketship full of food was parked right outside, because the drones decided it was more important to refuel the ship and move around waste-rock rather than offload the desperately-needed emergency supplies, hence why it'd be very nice indeed to have something similar for the drones....)

EDIT: On closer examination, it seems to almost entirely be an issue with the Drones. The shuttles aren't delivering food because the Drones leave it all sitting around in 'unreachable' places, such as in rockets or on farms, busying themselves with everything EXCEPT carrying it to the designated storage where the shuttles could get at it. Doesn't seem to matter what buildings you 'prioritize', either...