How would I randomly display decals, either specifically or randomly, from someone's inventory?

I am working on a game where elements of it, like billboards, would be randomly generated images specifically created for said billboards.

In order to not make the task tedious, I would like to make it where I would have a separate account where the images would be uploaded, hopefully approved, and then I would have a script pick an image from that said account’s inventory, without needing to hard-code anything in manually.

Say in the future I didn’t like an image either, I could just delete it from said account.

Is this possible? If so, how would I do it? Would I need to use something like HTTPService?

Yes, you will have to use HTTPService (obviously).

https://inventory.roblox.com/docs#!/Inventory/get_v2_users_userId_inventory

This is the endpoint that you can use to get the inventory. Use the asset type Decal and you get them all. Simple.

Remember that you will have to use a proxy since you cannot send HTTP requests to roblox servers internally.