Speaking as someone who volunteers at a soup kitchen, the one I help at has a garden that the guests and volunteers will work on during the warmer months and during the fall we actually used many of these vegetables for some of the dishes that we'd serve them for dinner. Even then we can't guarantee that they'll eat them.
One time in particular, the Sister who ran the soup kitchen received a few bushels of apples as a donation and tried to make a bunch of apple dishes for the guests, but that didn't go over well taking into account that many of the guests had whole rows of teeth missing. So, we tend to stick with softer things that don't require too much chewing. Even with the stuff we grow, that doesn't always guarantee the stuff they eat is healthy.
Often, I have volunteered to help serve food and I can't remember the last time I didn't have at least one guest who would skip on the vegetables, ask for extra gravy, or in the case of small children, outright refuse anything we serve them. We tend to keep some uncrustables in the pantry for this reason. A few guests will even refuse the meat for one reason or another(can't chew, vegetarian, picky) We often serve them small salads, but I don't recall us offering them options without dressing. One time I was helping to cook mashed potatoes for a dinner that night and I was surprised by the amount of butter and tard cum I had to put in. On some level, I get that it was because it was a dish to feed anywhere between 50-100 guests, but on the other I just felt like I might be slowly giving them a heart attack. It's usually better when my mom volunteers, since she favors the philosophy of "don't feed them anything I wouldn't feed my family or I wouldn't eat myself"