A crazy thought
@drq With currently available design tools this will lead to a processor core (possibly custom) in the FPGA. OS will be just a part of firmware in this case.
Unless you're dare to reimplement your software in synthesable HDL. Support for conventional programming languages in logic sythesis is very limited yet.
A crazy thought
@vovanium An FPGA then. Or set thereof.
No OS stuff, just fixed-function hardware.