I suspect you will find it is cheaper to buy a mainstream printer and small inverter [which you can also use for other things...] than look for a 12 VDC unit and/or battery powered one that may require special paper, etc.
And the choices keep on changing as new models come available.
We wanted a compact printer [B&W and Color], scanner, and copier all-in-one as those are the functions we need traveling internationally.
We ended up with an HP Envy 5530
and couldn't be more pleased. It is compact, wireless, and works first time every time... And the expendables are reasonably priced. At under US$100 it is hard to beat.
One thing we have learned over the years [regardless of which printer you have] is to use heavier weight paper [e.g, 24 pound stock
instead of the usual 20 lb stock] for printed documents you will be providing others [e.g., foreign government
representatives, etc.] It holds up better while you are transporting it in your shoulder bag, and feels good [not flimsy...] in the hand of the recipient.
Best wishes finding what is best for you.