When buying a firearm one of the steps is for your information to be sent to the FBI NICS system. That system will return either Approved, Pending, or Denied. As a person with a common name, I always get a “pending” but since my state has a waiting period this is a nonissue.
FFLs can’t transfer on a “pending” NICS result for 72 hours so it seems the Biden administration could create a de facto waiting period by issuing an EO telling the FBI to only issue a “denied” or “pending” status for the first 71 hours. Like Roe, it’s better to codify it but maybe there is something we can do until there is the political will to change the underlying law.