Grower feed is for meat birds. period. I wouldn't suggest using it it will make little difference
That's false. There's different "grower" feeds but most are appropriate to feed any chicken 6-8ish weeks and up.
Another option for OP is to feed a mix of your preferred grower/all flock feed and layer feed. I feed both to my birds to increase protein a bit while lowering calcium a bit. Though most of mine are happy to eat the large flake oyster shell I provide - any bird that needs calcium and won't take it, I mix in a small amount of oyster shell powder into a little wet or fermented feed for a private breakfast, 1-2x a week.