Where you need to be pointed, how fast you're going relative to something else, how long your burn needs to be, and when it needs to be. You don't need much "computer" to figure that out.

You can totally navigate space with just a pencil, paper, a slide rule, and a sextant. Like some kinda steakpunk steampunk space pirate.

Watched an interesting video recently about the computer used in the Apollo lunar missions. Of course even basic processors now are more powerful, but it's still impressive how rock-solid stable the Apollo computers were.

OP wouldn’t need it because their point is to say that the lander was just made from household items and staged to look like it was on the moon. To them, there’s nothing functional in that photo.