Food trucks can plausibly provide healthier options for food than in convenience stores, which often only sell junk food, according to a research paper that is a literature review [0]. This is especially true for low-income areas where there are fewer supermarkets (which sell fruits and vegetables) as due to the "risk of crime and theft, and [lack of] land for parking." However, the author writes that this hypothesis is not yet conclusive due to a lack of published studies.
Anecdotally, on university campuses, food trucks were the main option for food due to a lack of supermarkets and restaurants nearby. An app specialized for food trucks could also fix the problem where the availability and opening hours of food trucks are less known, especially for certain trucks that occasionally switch locations, are absent on certain days, or change their hours (making them hard to track via an entry on Google Maps).
In short, food trucks could plausibly be seen as a step up for finding fresh food instead of defaulting to a convenience store that may typically just serve junk food, in areas where there are no restaurants or supermarkets.
[0] Journal of Public Health Policy, 2021: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7874560/