It will be cool to have a dark theme for Service center and the outsystems.com site especially if you are using the Dark theme in Service studio
Investigating as a web developer you can open the CSS files of Service Center and the OutSystems website. In here you can see some references to light/dark-specific settings/graphics. So this is (being) developed. But not yet actively supported through profile settings anywhere.
I am sure when it is thoroughly tested, it will be made available to us all.