Hi there, welcome to BYC!
Bare minimum they will NEED access to some crushed oyster shell or other calcium source....
Beyond that... 1/4 acre is not really that much and it depends heavily on the weather and pasture quality.
People raised birds for years on scraps alone... it can be done. The birds just might not live as long as they would have... and the eggs might not be AS nutritious for the family.... you are what you eat. Production can often be slightly diminished (about 10%) not enough for most back yarders to notice but major for suppliers.
Most folks think of food scraps like rice and pasta or vegetables. This can heavily diminish protein and amino acids.... maybe getting enough depending on bug content of pasture but this changes seasonally in most locations. 22% protein was shown in studies to give the highest hatch rates, Noting vegetable protein and animal protein are not the same quality.
It isn't ideal... and I would consider adding a supplement like Rooster Booster brand Poultry Cell on occasion but that adds cost and defeats the purpose... but your friend can try!
More ideally... my free range birds on a lush acre in the PNW eat their
flock raiser ration first thing in the morning... and forage whatever else they can and want... saving me about 30% with ration available all day... But forage behavior is also heavily impacted by weather. At least eating the formulated ration loads them with essentials first.
Your friend can also feed the used egg shells back to the hens. They usually like them quite a bit but is not usually enough to negate the need for oyster shell free choice on the side. Simply make sure the shells are set so they dry and not stuck together where they can mold, then crush a LITTLE (not powder fine as it goes through the gizzard to fast to absorb that way) and put out there.
Molt around 18 months coupled with shorter days can make it hard for those hens to get enough nutrition... AND, FWIW... ALL things immune system related ARE effected by nutrition. To fully sustain a bird free range... my research shows they need 1 acre per bird, last time I looked into it.
I'm sure armed with plenty of knowledge and a helpful friend like you... your friend will figure out what works for their flock!