Can I use a spigot / dispensing spout on the 5-gallon carboy?

Yes, the hole in the center of the cap is designed to work with commonly available 2” threaded spigots / spouts. To use: 1) remove the cap, 2) drill a large hole in the center of the threaded hole in the cap, 3) screw the spigot onto the cap, 4) screw the cap back on the carboy, 5) turn the carboy on its side so the spigot points down and check to make sure the spigot isn’t leaking. Spigots are available at distributors, like at https://www.grainger.com/product/GRAINGER-APPROVED-Drum-Tap-6PFN4.