is it possible to use CEF python in headless mode for screenshots?

I could not get a clear answer on whether or not CEF python can be used in pure headless mode (no Xvfb or other) to take screenshots of the web page. I know about the offScreen option. But I don't see any option to set the size or viewport of CEF. And from my incomplete test, CEF doesn't load the URL if there's no X library used (GTK or QT, for example).

As far as I know CEF is based on Chromium engine which doesn't support pure headless mode on Linux. You can try at least starting X Server and check if it's enough to use CEF for screenshots. I guess running only X Server should be enough for this.