Smart Cities and Communities Act of 2021 This bill establishes programs for the implementation and use of smart technologies and systems in communities of various sizes. A smart city or community is one in which innovative, advanced, and trustworthy information, communication, and energy technologies are applied to (1) improve the health and quality of life of residents; (2) increase efficiency of operations and services; (3) promote economic growth; and (4) create a community that is safer and more secure, equitable, sustainable, resilient, livable, and workable. The Department of Commerce shall establish a regional demonstration grant program focused on facilitating adoption, and allowing measurement and validation of performance, of advanced smart city or community technologies and systems in a variety of communities, including small- and medium-sized cities and rural and tribal communities. Commerce shall also convene a Cybersecurity Working Group to develop tools for evaluating the cybersecurity of smart city or community technologies. The Department of Labor shall establish the TechHire Workforce Training and Development Pilot Program to furnish competitive grants for technology-based job training and education programs that provide an industry-recognized certificate or certification. The Department of Energy (DOE) shall implement a pilot program to improve the access of cities and communities to the expertise and infrastructure of the national laboratories to promote smart city technologies. DOE shall also expand its Technologist in Residence pilot program to include partnerships between national laboratories and cities or communities respecting research and development related to smart cities or communities. The bill requires strong federal encouragement and support for private sector-led standards-related activities. The bill requires the establishment of a strategic international smart cities and communities trade program.