Is it possible to replace an OS with hardware programs?

Call it an idea or an improbabilistic thought, but, can we do away with a huge OS & instead get hardware with embedded software, which works as an OS when all the hardware is assembled together? Of course, if we need to install any application into that OS later, the application would install requisite files & frameworks without hampering the working of the assembled system (assembled OS in this situation.)

Hoping for your critical & constructive feedback! Thanks!