Maybe I missed the memo, but since when has the Department of Homeland Security had the legal ability to grant pardons or change ones legal status ???
I have wondered the same thing. Apparently, Homeland Security has the authority to "pardon" people on a case by case basis for things like visa violations. So someone who has overstayed a visa can be "pardoned" and allowed to stay ... not made a citizen, but granted permission to stay rather than live in fear of deportation.
The scuttlebutt is that this corrupt administration is holding talks into whether it can use this authority to do a mass pardon.