There's at least partial support. According to
Ole-Egil's AmigaOne FAQ,
What are the options for stdin and stdout in the firmware?
The variables are:
stdin=serial
stdin=amikbd
stdin=ps2
stdout=serial
stdout=vga
Lack of VGA card will set stdout=serial and Ctrl-F12 on PS/2 keyboards will set stdin=ps2 and stdout=vga (lack of VGA obviously overrides the latter). The option amikbd is for the PCI Catweasel, you cannot connect an Amiga keyboard to the PS/2 input.