How long after cooking a foil wrapped potato can it sit in a warmer? For instance, I would like to sell wrap cooked potatoes and would like to know how long after cooking them are they good for in the display style warmer case?
Did you see this article on Wendy’s Baked potatoes? They found it challenging to serve foil wrapped baked potatoes, but have solved some of the holding issues by batch cooking the potatoes in foil (not recommended as russets are about 80% water and it steams instead of bakes the potatoes) and then holding the potatoes in bread warming drawers. This is a dry heat, but I assume you are talking about holding in a soup kettle or on a cafeteria style line metal 2-inch insert pan that gets steam heating to keep warm.
https://www.thrillist.com/eat/nation/wendys-baked-potato-fast-food
I’ve added a couple of links on foil wrapping potatoes. If you have to, I’d recommend wrapping but leaving the top open so the steam can escape, and then folding over to seal up the potato once removed from the oven. Usually the local health department determines how long you can hold them, which is typically no more than two hours, but I recommend no more than 45 minutes to keep the integrity of the potato, as the base will turn dark brown and outer skin will wrinkle.
https://idahopotato.com/dr-potato/why-i-do-not-recommend-baking-potatoes-in-aluminum-foil
https://idahopotato.com/dr-potato/foil-baked-potatoes