Saying the 3DS can't run android because it can't run Windows 95 is like, the definition of a false equivalency. Windows 95 was designed to run on an x86 instruction set, meaning that there's a huge amount of emulation going on between Windows 95 and the actual 3DS hardware.
Emulation causes overhead, and all sorts of issues. The 3DS is an ARM device and Android is, guess what- an OS designed to run on ARM processors primarily.
The problem with the 3DS running android is that someone would need to get android working with the 3DS hardware, and it would need to be a lite enough android version that it is capable of running on the limited resources the 3DS has to offer.
I'm guessing an n3DS could probably run Gingerbread or Jellybean or something super old that ran on much weaker smartphones of the time, given a competent developer taking all the time and effort to port it properly, but I think actually playing any android games or whatever is probably mostly out of the question. Just getting the OS running would be rather difficult I think.
