I mean, in this case, it literally is as easy as adding an alternate CSS style and then managing the proper dark-mode switching.

...not that this is really a concern in the first place. If you read through someone's blog and the best comment you have is on their website's OS integration, I think you've got your priorities misaligned.

To someone it's easy to recompile Nautilus with one of the thumbnails support patches or implement thumbnails generation via an external script.

Literally.