In the letter, Ms. Spruill points out that:
Charitable giving accounts for 2.1 percent of gross domestic product, a percentage that has not risen above 2.2 percent in 40 years. In 2016, about $390 billion was donated to charity, of which foundations gave nearly $59 billion. Just $1.4 billion came from megadonors. At the same time, federal government spending topped $3.9 trillion in 2016.
Clearly if you care about all children’s well-being after birth, you should probably support an expansion of Medicaid (not it’s elimination) and an expansion of the Supplemental Nutritional Assistance Program (not further cuts to the program).
For an example on the private voluntary approach to hunger in America see No Kid Hungry. See Link On Financial Information for financial details on fundraising and and administrative costs of the foundation.