I haven’t seen any youtube videos about it.
Well there is a way to create something like this. I would make a datastore that holds each players shop, and for every shop I would hold their data in a datastore and keep a list of stores using ordered data store. This way I can lookup player stores while offline and find the store data with the datastore.
It’s like how a leaderboard works, but instead of saving their numbers, you save their items. I would use a string value to save the name of the objects to their user id, when a player searches for their shop, it will load the user id of the player to find the string values (object names) and use a script to find objects in the server (replicatedstorage or serverstorage) then if a buyer purchases something then the server will match the string value with one of the said objects in the game