You can do digital pen markup on any number of stylus equipped Chromebooks using any of the excellent Android or Chrome apps for note taking and markup. Check

You can do digital pen markup on any number of stylus equipped Chromebooks using any of the excellent Android or Chrome apps for note taking and markup. Check out Keep, Squid, Google Classroom for Android, MyScript. There's even a handwiring mode on the soft keyboard that comes up if you flip them around to tablet mode. The feature is not just on the Pixel book. It's also in the $400 Samsung Chromebook Plus or Asus Chromebook Flip.