Comment by bluefirex

The dock uses a non-standard implementation of USB-PD, the Switch itself can charge just fine with just about any charger, though. As I understood it, the dock randomly switches between different voltages depending on load, while portable mode uses plain old USB-PD with a consistent charge. While you can use the dock with Apple's 61W charger, it's not really recommended, since it can still get bricked with a software update. The 87W/96W charger isn't safe for the dock at all.