I was exploring GNOME extensions when I encountered the Bedtime Mode extension. Its description states it was inspired by Android's bedtime mode. So, I looked up android bedtime mode
and found this Google support page.
However, judging by context clues and also other articles (such as this one from Android Police), this is only available through Digital Wellbeing, which is provided through stock Android with system-level Google Play Services.
Alas, it seems that I will continue to use the "Grayscale" color correction in the Accessibility options.