Obviously, these are domestic rabbits, just not very tame ones. The lack of early handling will make them very skittish, but they still won't have the honed instincts of the truly wild. If faced with real predator pressure, they wouldn't stand a chance.
My feeding program for baby rabbits is usually just grass hay, pellets, and water - the same things that their mother gets. If they seem to need a little extra for some reason, I may add plain rolled oats or calf manna. If this mother has been foraging in the yard, she probably has the right gut flora to support a diet like that, so these babies can probably deal with green stuff better than most litters of this age (most people warn against feeding grass or other fresh plant material until bunnies are at least 8 weeks old). The babies will have been eating the mother's cecal pellets, so their digestive systems will probably have been inoculated with the right sorts of bacteria.
Unfortunately, rabbits that are living on the ground are more likely to have internal parasites too, so you will need to watch for signs of worms or coccidia. Things have changed for them, even though it's for the better, and that translates into stress, and animals under stress are at greater risk for problems with diseases and parasites. You want to start handling them at least a couple of times a day, partly to gentle them down for their prospective owners (I assume you will try to rehome them, as you did with some of their older siblings) and partly so you will know if they aren't gaining weight well, or have loose stools, or any other issues. Rabbits are notorious for hiding problems; often the first clue that an owner gets is a dead rabbit.
Good luck!
