Ofcourse, porting Inferno to Amiga would require quite
a bit more
 effort to also support graphics etc, the Amiga doesnt have character
 modes, so you will have to implement a whole framebuffer and run a
 console on top of that (linux fb originates from the m68k port for
 exactly this reason). 
That does complicate things a bit.  However, if there's
an RS-232 port on the machine, then you could use
that for a console at least during initial development.
And in principle, osinit.dis could initialize the graphics
hardware and fire off the window manager, and you
wouldn't need to write the emulation of a character
mode.
BLS