Expanding SNAP Options Act of 2021 This bill revises the Supplemental Nutrition Assistance Program (SNAP, formerly known as the food stamp program) to make the online redemption of benefits, including the acceptance of Electronic Benefits Transfer (EBT) cards, more widely available by requiring the implementation of online SNAP purchasing in every state and providing funding for an online redemption portal and a technical assistance center. The Department of Agriculture (USDA) must award on a competitive basis one or more contracts to develop an EBT Online Redemption Portal to (1) allow program participants to use online or mobile electronic benefits transactions to purchase program foods from, and make online payments to, authorized program retailers under SNAP; and (2) facilitate food purchase delivery for program participants using such electronic benefits transactions. The Food and Nutrition Service of USDA must award competitive grants or enter into cooperative agreements with nonprofit entities to establish a SNAP Online Purchasing Technical Assistance Center to provide state agencies, authorized program retailers, and program participants information on and technical assistance with accepting SNAP benefits through online transactions and use of the portal. In providing technical assistance, the center must give priority to entities that are small and limited-resource retailers. The bill provides funding for both the online redemption portal and the technical assistance center. USDA must maintain on its website a publicly available listing, organized and searchable by region, locality, and state, of all approved retail food stores accepting benefits from recipients of SNAP, including through online transactions.