I seem to remember, certainly in OEM land there were dev.
systems with front panels and production systems without.
In other words the front panel was option and could be fitted.
Sure. The PDP8/f and PDP8/m are the well-known example. Many of the
Philips P800s had optional full panels too (fortunately the ones I own
do have the full panels). And there must be many more
But I still claim it is difficult to add a panel to a machine that was never
designed to have one. In the case of machines with optional full
frontpanels the machine was designed to take a frontpanel and either
to also run without it or there was some minimal panel (boot/reset/not
much else) that provided enough logic that the processor didn't realise
it didn't have the full panel (if you see what I mean).