The GPE devices aren't stock android in the Nexus sense, they're Sense and TouchWiz firmware heavily molded to fit the stock look/feel and to provide similar options. A custom recovery is not part of stock android by any means, and root alone provides very little use without third party applications unless you are using yourself as a development device. Being able to unlock and/or root a device is kinda sorta part of Android philosophy, but the listed items, Titanium backup, ad blocking and a custom recovery are not provided by Google at all. Stock Android ends at the device out of the box + updates they send to it. Anything you add or modify makes it different and thus not stock. That includes any custom recovery, custom kernel, any firmware modifications, etc.