Healthy Future Students and Earth Pilot Program Act of 2023 This bill establishes pilot programs for providing 100% plant-based food and milk options in school meals and expands access to nondairy beverages in school meals. Specifically, the Department of Agriculture (USDA) must carry out a pilot program to award grants for purposes such as training food service personnel on serving 100% plant-based food options and covering additional costs of buying plant-based foods. USDA must give priority in awarding pilot program grants to school food authorities that will use the funds to serve a high proportion of children who are eligible for free or reduced-price meals. The bill also requires a school participating in the school lunch program to substitute a nondairy beverage that is nutritionally equivalent to fluid milk, and meets USDA-established standards, if the student's parent or legal guardian submits a written request for such substitution. Further, a school has the option to offer each student a nondairy beverage as a substitute for fluid milk if it meets these same standards. USDA must also establish a pilot program to reimburse eligible schools for the cost of providing a nondairy beverage as a substitute for fluid milk. Eligible schools are those where at least 50% of the students served are eligible for free or reduced-price meals.