I have one that came with my iPad Pro. It charges my iPhone to 50% in like 15 minutes. The rest takes longer but it's pretty amazing for a quick top up a couple of times during the day.
I'm travelling tomorrow and thinking of taking just this brick to quickly charge my iPhone and iPad but I still have my Watch. I wonder if the Watch will support this if plugged in with a USB-A to C adapter.
You can actually order a USB-C Apple Watch charging cable. Sure, it’s $29, but I charge everything from my MBP. Great convenience!
https://www.apple.com/shop/product/MU9K2AM/A/apple-watch-magnetic-charger-to-usb-c-cable-03-m