Handgun Trigger Safety Act of 2021 This bill establishes a framework to regulate handguns as consumer products. The bill establishes two general requirements: (1) new domestically manufactured handguns must be personalized handguns, and (2) handguns distributed in commerce must be personalized handguns or retrofitted personalized handguns. A personalized handgun allows only an authorized user to fire the handgun. The bill directs the National Institute of Justice to make grants to develop technology for personalized handguns. It also requires gun manufacturers to retrofit, at an owner's request, a domestically manufactured handgun that is not a personalized handgun or retrofitted personalized handgun. The bill authorizes the Consumer Product Safety Commission (CPSC) to issue safety standards for personalized handguns. The CPSC and states may enforce violations, which are treated as violations under the Consumer Product Safety Act. The bill retains civil liability protections for gun manufacturers for harms resulting from the misuse of a handgun, but only if the handgun is a personalized handgun or retrofitted personalized handgun.