I've recently been playing around with Switch Homebrew and sideloading - mostly so I could extract my savegames to play games I own on PC instead using the Yuzu emulator (4K 60fps is more fun). Apparently Nintendo is quite good at detecting modified software on the Switch and will permanently ban and brick your hardware, so you need to go through great lengths not to connect to Nintendo servers when booting the modified or sideloaded software.