The working theory was the JVM was just a machine specification, which could, if you wanted, be implemented as an immutable processor (either a chip or a set of chips).

So if you can write a multi-user OS that only used the JVM (so it was 'Java all the way down') then you could build a Java chip for embedded systems, use a JVM for running it on a commodity processor, etc.

I had a lot of fun building the PiDP11/70 kit last year which is a PDP 11/70 built on top of simh on a Raspberry Pi. You can run BSD 2.1 on it which is decidedly Old School, but it (and RSX-11M+) are classical multi-user OSes. And that system has all the pieces of what we were trying to do with Java which is a virtual machine, compilers that converted code to run on that virtual machine, and an Operating system that can be compiled to run on it.