Another suggestion that came to my mind was being able to set the dark theme as the default one for all users (guests included)
Set default dark theme
This is an easy fix, it was already 95% wired in. So expect that to roll out today.
A word of explanation:
If you want only the dark mode to be available, you'll need to run your settings like the image below. Set default to dark, and untoggle the display feature. If you don't do this, the user preference will always be prioritized. Unless that user hasn't set a priority, then it defaults to System. Hope that makes sense. 🙂
