I don’t know about storebought dog food. But I have successfully fed green smoothies to a rottweiler, not mine but my mothers. She gets fed ice cream and junk food often and when I come over her legs are invariable trembling she’s sluggish and eyes foggy. I give her some smoothie and she loves them and will shamelessly beg for her dose of liquid fruits and vegies.
Instant perk up, legs stop shaking energy bright eyes etc and when I do this a couple days in a row she is literally another dog. But I don’t visit often enough to keep her regulated. However when I house sit for them I never have this problem with her.
I have another friend who supplements green human food for some of the meals for her show minpins and two schnauzers. Yes she cooks for them. But she does this in advance or in tandem with her own meals. Then freezes meal size portions for them later.