Exactly, you cannot be pardoned for future crimes.
However, I could image a court ruling that the violation of the immigration law occurs at the moment of the border crossing and then the crime ends once the border is crossed.
If that was the case, one could be pardoned for a illegal border crossing that occurred in the past.
“I could image a court ruling that the violation of the immigration law occurs at the moment of the border crossing and then the crime ends once the border is crossed.”
Then a bank robbery ends when the robbers leave the bank.
Then we might as well nullify all the harboring of illegal alien laws, too, if staying in the country illegally is not a crime once the illegal entry is concluded.
-PJ