Google News for Android now includes a dark theme. The feature is included with the update to version 5.5, which is now rolling out. Once you've updated, go into the apps Settings section and you'll find the dark theme toggle in the "General" section. There you'll find four options: Always, Automatically (at night and battery saver), Battery saver only, and Never.
You can see some screenshots of the Google News app's dark theme above. It does about what you'd expect, changing the background of the app to black and the text to white, which should help ensure that you're not blinded when you open the app in a dark environment.
The update to Google News v5.5 is now rolling out in the Play Store, so keep an eye out for it.