Securing Guam's Shores Reimbursement Act of 2023 This bill requires the Department of Homeland Security to make grants to Guam for expenses related to security measures associated with non-U.S. nationals ( aliens under federal law) unlawfully entering the territory through the shores. Additionally, no grant may be used to reimburse nonprofit organizations, fund legal representation, or provide educational, housing, food, or health care resources to non-U.S. nationals who unlawfully entered the territory.