Short answer
Yes, a tiny amount of vinegar mixed into food is generally safe for a puppy, but you should never let it drink straight vinegar. The acid can irritate a sensitive stomach, so keep the quantity very small, like a few drops or a pinch in a meal. Watch for vomiting, diarrhea, or excessive drooling, which would indicate irritation. If any of those signs appear, give your vet a call for advice.
Vinegar — Food safety facts
Feed with care · Dogs · full breakdown on the linked food page
Acidic and irritating. Small amounts in food are harmless, drinking it is not.
The full verdict, portion guidance and serving notes are collected on the Vinegar food facts page.