Here’s the problem with shipping phones and other gadgets, which inevitably must be plugged into a socket at some point, without a power adapter: technology advances, standards change, and often times your old power adapter won’t work with the new device.
Case in point: Apple’s own MagSafe Duo charger, which (amazingly, for a charger) comes without a power adapter, isn’t compatible with Apple’s old 29W, USB-C power adapter. I say “old” but it’s not really that old — it was replaced by a 30W power adapter in 2018. So there’s actually quite a big chance that you still have a 29W power adapter which you won’t be able to use with the MagSafe Duo.
This is according to Apple’s own support document for the MagSafe Duo (via AppleInsider), which clearly states: “The Apple 29W USB-C Power Adapter isn’t compatible with the MagSafe Duo Charger.”
The 29W USB-C power adapter might still actually work for you, but it probably won’t be able to simultaneously charge an iPhone and an Apple Watch, which is the point of the MagSafe Duo.
Apple stopped shipping power adapters with some of its products released in 2020, most notably the iPhone 12, citing environmental reasons. And yes, a lot of folks have an old power adapter at home, and don’t really need a new one. Those that only have a 29W power adapter and have purchased the MagSafe Duo will surely be slightly annoyed, though.