Hi, this video shows you how to get a keyboard and mouse working on the Nintendo Switch. This is not supported by Nintendo and if you were using MODs to cheat in online multiplayer games then it could lead to a ban.
This video shows the setup that you need. You will need a PC/Laptop, CronusMax Plus and a PS4 to Wii U Brook Converter. You would think that it would cause a huge amount of input lag but amazingly it doesn't, I can't detect any lag but I am not the best gamer so what is not noticeable to me may be noticeable to you.
It is a pain to setup first time but once it is setup then it is quite simple to set it up each time you want to use keyboard and mouse on the switch. It is ideal for FPS (First Person Shooter) games like Doom.
Many thanks Vince