In search of the dark mode holy grail

I've been thinking a lot about dark mode lately, now that macOS and Windows 10 both officially offer some implementation of it. I think dark modes make a compelling case for eye strain prevention, but the dealbreaker for me is revealed when switching between apps and one of them isn't dark. That jarring flash of bright light completely ruins whatever gentleness the dark environment provided in the first place. So despite my curiosity I've kept everything in light mode for years, tempered by f.lux to keep myself sane after sundown.

Anyway, now that there's official OS support I'm reconsidering. I think there's a growing pro-dark movement that was just waiting for that formal recognition. Today the programs I use most all offer dark modes so I'm taking an experimental plunge. My goal: 90% elimination of white flashes while in my normal workflow.

The biggest obstacle is, not surprisingly, the web. There are some beautiful dark browser themes available but that really only affects the UI elements around the page, not the page itself. I want to darken the web too. I have a few thoughts about this:

• Plugins like this one try to automate a dark mode for every site you visit. This is hit-or-miss, resulting in ugly color combinations, sometimes unreadable text. Some methods just invert the page colors, which can lead to all sort of other visual wonkiness. I haven't found a plugin like this that isn't fiddly and annoying.
• This plugin looks interesting. From what I can tell, it uses some kind of server-side heuristics to determine the optimal way to darken every page you visit. I haven't actually tried it because I'm concerned about the privacy/security implications of sending all my web activity to this unknown third party. Or what kind of performance hit that would involve. Also, they bury this information on their site, but this is a paid service with an annual subscription.
• I'm aware of Stylish and its huge library of user-maintained custom site styles. This seemed like a good approach, except that following a recent acquisition, the new owners of Stylish betrayed their users' trust in a very shady way so I'm afraid to go near it now. If there's a credible alternative with a decent style library I'd love to know about it. Especially if there's a way to automate style application so I don't have to manually activate it for every site I visit.
• Tangentially, the W3C is having an interesting conversation about adding CSS media query support for recognizing user dark-mode preferences. This could absolutely be the future of the web(!!), but I suspect it won't because it puts the responsibility on designers to basically double the amount of work they have to do. Speaking as someone in that field, I would not want to have to add this to my already-long list of design considerations.

Are there any other good web darkening methods I've overlooked? How do you deal with the white flash problem? Should I just give up and go back to black-on-white? Interested in any and all thoughts on the matter.