In Star Wars set 6211 there is a part number 46212pb001. (Hologram image of Emperor
Palpatine). This is every much a Minifigure just as Minifigures sw1162s, sw1123s
and sw1169s are.
In the catalog there are several Minifigure numbers that are not being used.
I suggest that you use sw0185 as this number is not used and comes close to the
numbers being used in the set itself.
Other unused numbers are:
sw0186
sw0276
sw0353
sw0470
sw0484
sw0549
sw0563
sw0564
sw1144
[...] A hologram is not the character, it is a projection. Whereas the character is frozen in carbonite. (15 months ago, Feb 17, 2023, to Catalog Requests)
[...] According to our revised minifigure guidelines that we have been working on, it is not a minifigure or figure. It is a hologram. And the other "minifigures" [...] (15 months ago, Feb 17, 2023, to Catalog Requests)