Protecting Critical Boards and Electronics Through Transparency and Enduring Reinvestment Act of 2021 or the PCBETTER Act of 2021 This bill provides funding for and otherwise addresses the electronics industry as it relates to national security and Department of Defense (DOD) programs. The bill establishes in the Department of the Treasury the Electronics Supply Chain Fund to create a commercially competitive electronics industry in the United States that is capable of meeting national security needs. Among other activities, the fund must be available for DOD to (1) fund the construction, expansion, or modernization of facilities to develop or manufacture semiconductors, microelectronics, advanced electronic packaging, and printed circuit boards; and (2) carry out a program (established by this bill) to test DOD systems for vulnerabilities to foreign interference, sabotage, espionage, and attack. Providers of certain electronic systems must provide DOD with a list of the printed circuit boards in their system that includes an attestation of whether (1) the printed circuit board was partially or fully manufactured and assembled in China, Russia, North Korea, or Iran; (2) the printed circuit board was fully manufactured outside of those nations; or (3) the provider cannot determine where the printed circuit board was manufactured and assembled. DOD must designate a senior official to remediate any vulnerabilities discovered by the established testing program. DOD must promulgate regulations to require contractors selling goods or services to DOD (e.g., printed circuit boards) to undertake such due diligence as DOD considers appropriate to prevent the occurrence of vulnerabilities.