I read a dog training quote that said “If we give our dogs treats, rewards, and praise for nothing, what are we left with?”
The vast majority of federal agencies using dogs prefer toy reward to food reward. There are good arguments for both. Your puppy will take time to develop the extreme desire to possess the ball, so in the interim we need to keep them busy developing towards a goal. I love food machines for “shaping learning”. Their value is seen in being able to get multiple behaviors per session and the machines never get angry, change tone, or give confusing cues. Since the reward comes from machine rather than the handler, this technique develops independence from the handler. Food as a reward should be faded as the dog develops extreme possession of the toy. There are videos on the Olfactory Training page about use of food machines.