Protecting American Heroes Act of 2020 This bill provides funding for the Strategic National Stockpile and expands certain authorities under the Defense Production Act of 1950 to support domestic supply chains for medical countermeasures and other supplies procured for the stockpile. It also makes changes to reporting requirements, threat-based reviews, and other aspects of the administration of the stockpile. Specifically, it authorizes the Secretary of Health and Human Services and the Administrator of the Federal Emergency Management Agency to use authorities under the Defense Production Act of 1950 during a declared public health emergency to the same extent as the President is authorized to do so. Currently, that act confers upon the President a broad set of authorities to influence domestic industry in order to provide essential materials and goods needed for the national defense. In addition, the Government Accountability Office must assess any plans related to the domestic supply chain in its annual reports on the stockpile.