My little dog ljust loves snow peas (in the pod). I cut them up and we do "training" with them. It is treat time, but she has to do something to earn them. All dogs need to work on manners and I like to mke it fun.
Your new rescue might have been a snacker all day and feel deprived at first. Maybe a few in-betweens might keep him from worrying about the next meal.
Have fun together. Does your little guy like to go for walks?