Conservative groups influential with the Trump administration have pressed for the preemptive acts of clemency.
There’s a world of difference between a pardon issues to prevent malicious prosecution for non-crimew and one issued to people you’ve been instructing to commit crimes



The President has not been granted the power of amnesty over immigration violations.
Consider that President Obama tried a much narrower executive action to exercise prosecution discretion over immigration violations, and that still faced some very stiff scrutiny from the courts. If Obama had an amnesty power, he would have probably used it.
Presidents do have a few other levers to let people enter and stay in the country on their discretion:
Sorry I was tired, I was thinking of the Reagan amnesty, but that was an act of congress that he signed.
https://en.wikipedia.org/wiki/Immigration_Reform_and_Control_Act_of_1986