In the update seen above, the new shopping cart item advertises the ability to "Roll into battle alone or with a buddy!"
An Epic Games representative said the shopping cart is expected to arrive this week, but declined to offer exact timing. It's not clear just yet how the item will work, or even how it will appear in the world. If the recent jetpack addition is any indication, it's likely that shopping carts will be a usable item found in the world — like shield potions or weapons or med kits.
Vehicles have been a staple of the "Battle Royale" game genre since "PlayerUnknown's Battlegrounds" launched in March 2017. They've been a long-requested feature in "Fortnite," and it'll be interesting to see how they impact the game.
Given that we're talking about a shopping cart instead of, say, a car, it sounds like any riding will be a one-way trip. But we're also talking about a game with a magical floating bus and a surrealist, often Dali-esque world — it's entirely possible that these shopping carts come with propulsion. Epic wouldn't tell us anything more.
We'll see later this week when the update arrives.