While I believe that a minimalistic approach could work on an 80286, an 08186 or 08086 in just plain fantasy.
As for the supposed "pre-x86", that would be the 8080 microprocessor developed by Intel prior to the 8086. Before that there was the 8008. Personally I would love to see someone get GNU/Linux running on a 4004. It was Intel's first microprocessor and it ran at 108KHz (yes that's a K).