Here we go guy,
Here's a big project for all Xperia X family
I've successfully ported the Xperia XZ2 theming engine to various Xperia, what does it means? When Sony launched Oreo on his devices, the first thing that users noticed is that the themes were not theming all UI as prevously.
Only wallpapers, theme accent and home launcher were still themed but not the whole UI like the spinners, scrubbers, buttons, action bars, app backgrounds, ...
With the Xperia XZ2, Sony add back full theming engine like it was on Marshmallow or Nougat.
I've ported it to all my eXistenZ rom and now I will share it with more devices. Also I will write a tutorial for all other Xperias devices running Oreo so you will be able to do it by yourself.
I'm also adding the Xperia XZ2 systemUI adapted to support full theming with new Loop lockscreen clock
Take a look at the attached screenshots to see how it looks when all is themed
This thread will be updated soon
Video comparaison with and without full theming engine by @Jozinek: