Mono audio is an Accessibility feature of Windows 10 that makes sure that a listener will never miss a sound of audio playing in a stereo headset.
winaero.com
Not what I wanted. I wanted to enable it for one output device, without having to constantly change between enabling it for my speakers and disabling it for my headphones.
I figured out a solution though. I downloaded Voicemeeter Banana and just set mono audio there. I will use that as my default speakers device and continue using the same headphone device.
Thanks for trying though.