Living in a farm community, I've never had to label my eggs as everyone knew where I lived and could see my chickens ranging all day, every day. They also know where I buy my feed, so they don't get into the whole health benefits of the eggs~they just assumed they were healthier than the battery farms down the road. I just sold them to whoever will buy them and that was plenty of folks.
In towards the city, I'm thinking you have a more picky crowd of customers? I'd just say they are fed naturally as possible and leave it at that. I never did organic, GMO or soy free as I consider my eggs a premium product despite not adhering to some mysterious guidelines that can't really be done...not really. It's literally impossible to live on this Earth and market organic eggs..there are chemicals in all our soils and deposited onto our grasses as the chemicals fall out of the atmosphere. Vegetarian chickens? Really? They don't snatch up a bug when they see one?
Non-GMO crops can be tainted with GMO pollen, though they try to prevent this as much as possible in some areas...where I was living they didn't try at all. You got what you got and Monsanto wasn't breathing down the necks of these small time farmers.
GMO and soy are just a fact of life now unless you want to pay through the nose and drive 50-100 mi. one way to find someone who has that type of grain/feeds...and that defeats the point of selling eggs, as you will never sell enough to defray that feed cost. If you have that kind of resource next door, that's a neat thing and can be accomplished, but not many do so it's a moot point.
The way I get around these issues without creating more work and more overhead costs is to free range and supplement in the evenings if needed. The eggs look good, taste good and perform well in people's GI tract and systemic body, so I count that as good. Where I live you can't get more than $2 a doz. eggs no matter what special dance you do to make them extra special healthy, so what's the point? If I count them healthy enough for my family, I feel good about marketing them to others...and all my customers were glad to get them. If they weren't, there are always people standing in line when they step out of it.