This is going to sound weird because it is. One time I wondered if I could plug my Switch while docked to my laptop, it didn't work because my laptop only has HDMI out, not an HDMI in.
Anyway today I was doing a digital painting for Linktober and I realized I could go HDMI out from the Switch dock and use my Graphic Tablet for the input, and sure enough it worked! I can use my Graphic Tablet as a monitor for the Switch while docked. The only downside is the tablet has no audio function, but I suppose I could use the Bluetooth Audio function on the Switch with my Bluetooth Earbuds.
Cool to know, not very practicial right now, but if I'm ever traveling and end up in a hotel or something with no TV and I want to play Switch games on a bigger screen this could be a solution.