It seems that the doll will most likely become a human eventually. On the contrary however, if it dies before achieving it's goal, I wonder if Fushi will be able revive it, since it's apparently an electromechanical device and not a living organism, and thus possibly lacks a soul. Unless kaibara...
One of the parts that I liked was that the ML wasn't reincarnated but instead was teleported to the new world.
This implies that the ML is actually around the same age as the FL rather than being a middle aged man or an old aged man (with combined age from current and past life).
I did feel similarly for my little mouse too. But it was more of a horrifying guilt for a horrible deed. I fed it few drops of ORS solution after which it became more and more numb and eventually died few hours later.