All Flock and Oyster Shell on the side, yes. and as many discovered, "Starter" and "All Flock" formulations look a lot alike, nutritionally. Plenty of us subbed one for the other during the Pandemic when choices were few.
The biggest difference is that starter is much more often medicated, but it should be easy to find unmedicated starter. The medication used here in the US most commonly is Amprolium. You can ABSOLUTELY eat eggs from chickens getting Amprolium in their diet. Its a thiamine antagonist, meaining it blocks thiamine uptake. Eating enough eggs to have any effect on a human mass would be far more unhealthy than the amprolium itself, and its effects could be treated immediately and w/o further consequence simply by taking a B-vitamin. There's greater risk of thiamine deficiency from having a beer every night than two eggs from an amprolium treated bird at breakfast.
As to why you have trouble finding Organic all flock? Its complicated, but the main reason is that "All Flock" feeds have significantly more crude protein than "layer" type formulations, and typically a higher relative percentage of methionine (critical for developing birds, less needed in adult layers). Organic, high protein, high methionine sources are hard to find and expensive. That's changing, but it certainly impacts the current product mix.
Best chaces are a feed containing organic porcine blood meal (yes, dried blood from organically raised pigs), organic insect meal, organic soy meal, or similar. No I don't have any recommends unfortunately.
