The motors at 27V are high voltage, probably tin-can steppers, and probably a high angle so indeed not much use for them, probably unipolar too.
However, salvaging stuff is an art you need to live with 5 euros/day to appreciate it There is more to it than just steppers.
If you salvaged the psu from that printer aswell, you could have psu for them already. Its probably low power, and would only work with those 2 and some logic, but you can underdrive the steppers or push the supply a little and make room for a 3rd stepper, should have that extra space. So psu=good too - it already has the voltage you want for those motors, and probably has a 5v line out also, but dont confuse it with "power good" or "power status" that some supplies have.
Else with a 7805 and few caps you have a logic supply for a mcu. I doubt there is a 7805 on those electronics, but some switching logic regulator is somewhere there, maybe 5v even, and probably has all the caps nearby.
If you want to push things to extreme, find the stepper driver ic on the electronics, and download and read the datasheet - and bang you can use those too, and as a bonus for reading datasheet, they have already all support components nearby.
Dont be afraid to do whatever. And if anything goes wrong, you burn something, remember its all good since you didnt had anything to start with! So its probably the best way to learn - on the cheap.