Have a look at http://maruos.com/, the dev has an interesting idea - AOSP when the phone's working by itself, plug in a Slimport connector and pair a Bluetooth keyboard and there's Debian running, ready for you to use.

I'm not sure what's going on with the project. Two months later you still have to email the developer to get a beta build, even though it was supposedly open sourced.

Approaching it from the other direction, https://plus.google.com/111524780435806926688/posts/fkQ1BMjN... shows a nearly mainline kernel running on the 2013 Nexus 7, including hardware accelerated graphics. It should be a hop skip and 14 hour build step [1] to get Debian running on it.

[1] repo sync -j24 / make -j24 droidcore can be painful