Overjoyed: an accessible virtual gaming controller
This Windows app provides a mouse-based virtual controller that can interface with a Nintendo Switch by way of a physical control from 8BitDo. So you need the 8BitDo Micro Bluetooth Gamepad. Then you install Overjoyed. Once you do the setup process, you can hover your mouse over the virtual D-pad to trigger the same directions on the Switch. There are a ton of additional features like allowing mouse click to trigger secondary actions and all sorts of other useful settings.
I’m on a Mac, but I was able to install Overjoyed in a Windows VM using UTM and it worked great.