I had a 1975 F100 full size pickup with disk on front, drum on back, manual brake - no vacuum boost. They worked fine. I actually feel they were more responsive and easier to pump them a little when needed due to no ABS.
My dad had an 1988 GMC S15 with zero options he bought used when I was a kid. No power steering nor brakes. disc front, drum rear. No AC....
My Porsche 914-6 had 4 wheel, manual disk brakes. They were a bit on the wonky side, but when quality pads were chosen, and "just bedded in" new, they worked well, with a firm, hard pedal. However, the pads did wear oddly, despite my best efforts, and were useless junk in short order. They lasted no more than 5000 miles for me.Early Porsches had manual disk brakes.