I don’t think SW Dark Forces was even designed to be played with KBM. You might have suceess with mapping mouse movement to swipe controls in Magic Dosbox, but I’m not sure if any of this could be translated to a Chromebook w/ external mouse in a playable fashion.
I found this though: https://www.gog.com/forum/star_wars_dark_forces_series/dark_forces_plus_basically_vanilla_mouse_look_an_alternative_to_darkxl/page1
Seems to add some kind of mouse support to the game, so maybe this can help?