I just got an Nexus 6P, and unlike with my previous phone, I would prefer to keep the firmware as stock as possible this time while still enabling debugging/root access. (for app development) On my earlier phones, I used CyanogenMod because I wanted the features, but conveniently, it happens to ship as a userdebug build. This time, I would like to stick as close to stock as possible.
I found the official factory images for Nexus devices, but it looks like they only have the "user" builds, and I know Google does build official "userdebug" and "eng" images, because I've seen them before, but now I can't find them. Have they been deleted off the Internet?
Worst case I suppose I can build them myself from source, but I'd rather use the official images since I'm not going to be hacking on Android itself (at least not yet), and I'd also prefer to avoid having to rebuild every time there's an update. (it also requires a lot of disk space, more than I currently have free on my laptop, and the build system is too architecture-dependent to run on my server)
So, the question is: Is there an easier way to get a userdebug build for Nexus 6P? (or Nexus devices in general)
Alternately, is there some way to de-cripple USB debugging so I can debug the released version of my apps and either get a root shell or at least have some other way of seeing my own files?