Type 6/7 "UNIX" keyboards

I've got some surplus Sun USB keyboards, in mint condition too.  One
is Type 7 with PC layout and dip switches for layout selection at the
back - bog standard.

The Type 6 one and the other Type 7 one have "Unix" layout:

  https://docs.oracle.com/cd/E19253-01/817-2521/new-311/index.html#new-fig-349

There are no dip switches.  The Type 6 is easy to open, I don't see
jumpers on the board either.  Type 7 looks more tightly built and I
don't really want to pry it open (I'm all thumbs) most likely for
nothing.

I gather it's impossible to change their layout except at the
driver/xkb level.  Could someone with experience confirm that?  TIA.

-uwe