As far as I can tell, it doesn't matter what pellets or food is labeled, when mom eats it she develops the right gut bacteria to deal with it, and passes that on to the kits. All my kits had access to moms food, no issue.
Rabbits evolved on a meager diet. Sure, with optimized protein for max. growth you'll get to butcher weight asap, but that isn't a goal for me. IMHO healthy growth can be slower, the final size is mostly determined by genes anyway.
Raising rabbits isn't rocket science. There is a reason why they were an important food source in my area even 40 years after the War.
What I strive for is a diverse diet with hay, many grasses and weeds, and pellets as a supplement. Well, I feed everything that grows around here, and pellets are the treat to get them back in their hutches in the eveneing. They start to get out in the garden and forage at 3-4 weeks.