Answer:
To view Nintendo Switch gameplay on a laptop, you need to buy an HDMI video capture card. This is necessary because laptop models generally don’t come with support for HDMI In functionality.
Any capture card can be used for this process as long as it has a USB-C connection and an HDMI In port. There are several great capture cards to choose from, but Elgato cards are generally considered the best option by gamers due to their affordability, build quality, and ease of use.
For these instructions, we use an Elgato HD60 HDMI capture card and the free Elgato Game Capture HD software. The capture card can be purchased from Amazon while the software can be downloaded for free from the official Elgato website.
(I have a Switch and I've done it)