Border Security for America Act of 2021 This bill addresses border security and related issues. For example, the bill requires the Department of Homeland Security (DHS) to resume all activities to construct a border barrier system along the U.S.-Mexico border that were underway or planned prior to January 20, 2021; requires DHS to deploy, in addition to physical barriers, tactical infrastructure and technology to achieve situational awareness and operational control of the southwest border; authorizes U.S. Customs and Border Protection (CBP) to carry out a program to acquire innovative commercial items through a competitive selection of proposals; imposes certain requirements for DHS border security technology acquisition programs that have a total expenditure of at least $300 million; requires CBP to implement certain technologies, including a program to establish a biometric exit data system at ports of entry; requires CBP to increase or maintain certain staffing levels for agents, officers, processing coordinators, and other positions; requires CBP to implement a workload staffing model for the U.S. Border Patrol and for CBP's Air and Marine Operations; and provides statutory authority through FY2026 for Operation Stonegarden, a Federal Emergency Management Agency program that provides grants to states and territories involved in certain active CBP border security operations.