There's significant case law going way back that gives state and local governments broad police powers in public health emergencies. It's considered a power reserved to the states by the 10th Amendment. Vaccine and mask mandates have been enacted before, with the courts' blessings, by state and local government. The federal government, no. And there is no question the current Supreme Court would shut down any move by the federal government to mandate anything, including passports. Biden's hands are tied on this.