Once upon a previous century I tested a laptop with a built-in printer for an article I wrote for a magazine. Paper was fed through a slit underneath the keyboard, ink was dribbled on it from a microscopically small ink cartridge and in only half a minute it worked its way through a single A4 sheet.
It was made by Canon under the name Notejet [1]. It did not come with a built-in desk though.
Not built-in, but https://youtu.be/2nR3dDVgAVQ?t=51 is someone using a HP 200LX MS-DOS based palmtop and battery powered portable battery powered small Pentax printer, in 2015.
I didn't recognize the movie but the two onlookers are John Turturro and Mel Smith - which pegs it as Brain Donors (1992)
https://www.imdb.com/title/tt0103872/
It was made by Canon under the name Notejet [1]. It did not come with a built-in desk though.
[1] http://laptop.pics/canon-notejet/