Not what you are asking, but I use this bookmarklet to make any site dark mode.
It seems like everything else I’m using often enough has dark mode built-in.
javascript:(function(){body=document.getElementsByTagName('body')[0];body.style.backgroundColor='#333';body.style.filter='invert(100%)';})();

writen by Kirill Rogovoy
If you don’t know what a bookmarklet is, it’s essentially a bookmark in you browser that has JS instead of a URL.
When you click on it, that JS executes against the current page.

writen by Kirill Rogovoy
Just like you create a normal bookmark but paste that JS snippet instead of a URL

writen by Kirill Rogovoy
Yeah it just inverts color. Which works in 90% cases in my experience. It also fucks up images. But hey, it took a minute to set up, and you are in control of the code. 😊

writen by Kirill Rogovoy
You put <chrome//flags>
and you can access special features that are not enabled for most people, like the url bar on the bottom, or forced dark mode

writen by Bartolomeu Rodrigues
It also has some cool utilities for debugging like a flag that considers the localhost as secure (as https), so you can develop progressive apps locally

writen by Bartolomeu Rodrigues
Anytime. I found them because I also wanted dark mode but it wasn’t a thing back then

writen by Bartolomeu Rodrigues