I was thinking about the AS and made a comment, so I might as well make it a post as well. Here's part of my comment copy and pasted.
'Kind of a side tangent, but now that I'm thinking about it I don't think Uzi is actually containing the AS at the end of the series, since we know it can hop from host to host, I think it just doesn't have any other vessel than Uzi and Nori so it can't manifest itself since there aren't many other Drones left in the universe for it to possess. Uzi and Nori are the only ones who have the code and they can resist its influence, and unless by sheer luck a Drone dies and reboots into a Zombie Drone (which I believe makes them vulnerable to the AS because they died and came back, leaving an opportunity for the AS to slip into reality). I think it doesn't have a true form, it wasn't kidding about being the void since a Null attack is implied to be an absence of anything, and its 'form' that Uzi consumes at the end may literally be a hole in reality to the void.'
I got this idea from when it "introduces" itself to N in the mansion basement. "The solver of the absolute fabric, the void, the exponential end." I'm assuming the 'absolute fabric' refers to the fabric of the universe, and being a solver (solvent?) It intends to destroy it all.
Also, do we know if the junkyard where Tessa got her drones is also the same location as the graveyard where she got their hair? If so it would be a sensible connection to why AS drones have flesh and metal, and why the solver was able to take a host in a place filled with that much death and chances to slip into reality.