The president’s pardon power has no limits....................
This is not a pardon for a conviction of a crime. This is a dodge around the legal requirements for immigration, a power reserved to the Congress.
I’m certainly not a Constitutional law expert, but since none of these illegals have been charged with any crime related to their illegal status, I doubt Biden could pardon them. Of course, this regime has well demonstrated that they are entirely lawless and are willing to ignore even Supreme Court decisions, so they’ll probably go ahead and try anyway.