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sigh. the SNES is NOT a PC. the hardware and software specifications are completely different from any other system.
Besides- windows 3.1 requires DOS, DOS is an operating system, and the SNES works directly OFF of ROM, so it doesn't HAVE a boot cycle to ANY OS. Same story for NES as far as running off of ROM.
So, you consider, "well, we can try to adapt windows to run in ROM" Not a feasible solution; windows, and DOS, in general assume that people have some form of disk drive. the only way to facilitate that would be through SRAM. except that even the largest SRAM chips generally hold less then 80KB- usually only 16KB.
Even so, DOS would need to be completely rewritten in order to even run on an SNES; since the SNES has a completely different set of specifications, including endian format as well as memory layout (and in the case of the NES bank mappings) Unfortunately the DOS source code isn't exactly available, and even if it was over 50% of it is assembly and difficult to either understand, and in the case it is understood, change.