Try the "Dark Reader" plugin (works for all chromium-based browsers and Firefox - at least). It lets you customise the "darkness" of the dark mode to your hearts content. I have most of my sites set up so that they're more "very dark grey" rather than black.
Doesn't always work nicely, some sites get their images mangled, or the text will get a weird shade that makes it illegible, but overall, it's great. And you probably can fix most of these issues by tweaking the filter settings.