Bob Gardner wrote:


Can Clearance Delivery (through an RCO on the ground) give a pop-up
IFR instead of Approach?

No, CD has no airspace.


So far I have found that they ask me to call
Approach when airborne, or file with FSS. Is there an operational
consideration that prevents CD from giving a pop-up?


Yeah, he's not the approach controller. It would be the same as calling
ground control for your takeoff clearance.