prompter Hi there!
I understand that some of the AOSP apps that come with the OS are not ideal right now, and lack of dark mode is part of that.
The project has already added dark mode for some of the apps that didn't previously have it and is still interested in doing it for other apps, but as you can imagine, that's low priority compared to security and privacy enhancements.
Some of the apps are also eventually going to be replaced (apps such as the AOSP gallery are an example) with much more modern alternatives.
I would recommend against messing with developer options generally. They often don't work as intended to (as you have experienced) and are more likely to break things rather than fix them.