Re: a totally non-Unix-like system
"I seem to remember Amiga being at least inspired by UNIX. It certainly wasn't POSIX or anything, but commands, libraries, and startup scripts, and configs were all just directories in the root of the filesystem."
AmigaDOS was based on TRIPOS, no relation to Unix at all. It had a command line interface, but this was not a shell. That said, within a couple of years there were numerous *nix shell-like shells for the Amiga, Bourne Shell, csh, ksh, all can be found on the early Fred Fish disks.
C= released a SVR4 Unix for the A3000 - or the A3000UX to give it it's marketing name. I never used it.