Small Business Disaster Relief Equity Act of 2020 This bill makes state-legal cannabis businesses eligible for disaster assistance, and it requires each agency that administers disaster assistance to allow these businesses to retroactively apply. Disaster assistance is any service, grant, loan, tax credit, tax deduction, or any other assistance that is made available in connection with (1) a federally declared disaster, or (2) specified COVID-19 (i.e., coronavirus disease 2019) relief programs.