Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that your fellow ingested some glass from a broken sauce jar, and I understand your concern.
The short answer is that while things look good so far I don't believe we are out of the woods yet.
The good news is that he is a big dog, he is eating, and it has been two days with no evidence of vomiting, black tarry or frankly bloody stools, a fever (rectal temperature greater than 103F), or abdominal pain. Those are big positives in his favor.
Most things ingested pass within 48-72 hours. If the glass pieces were smaller they could get caught up in intestinal folds, so it could take a few more days. But smaller pieces are also less likely to perforate an intestinal wall.
I suspect that they gave him a high fiber food to cushion sharp edges and help bulk up stools to carry the pieces through. I would feed small meals of a high fiber food for about a week if this were my fellow. Small frequent meals keep the gastrointestinal tract moving and being always full keeps the intestines from contracting on just glass pieces.
After a week's time of him remaining well then you can slowly transition him back to his normal diet and regular number of meals. It should take 5 days or so of each day slowly adding more regular diet, and less prescription food, to his meals to properly transition him back.
Please let me know if you have any further questions.