NEW - Biden says "The president wrote a very generous letter," referring to Trump. "Because it was private, I won't talk about it until I talk to him. But it was generous."
This taken from the US Military Voice Telegram Channel.
I'm betting the 'generosity' was the deal Biden cut with Trump...
The word you're looking for is amnesty.
"A pardon is distinguished from "a commutation of sentence," which cuts short the term; "a reprieve," which is a temporary halt to punishment, particularly the death penalty, pending appeal or determination of whether the penalty should be reduced; "amnesty," which is a blanket forgiving of possible criminal charges due to a change in public circumstances " https://www.law.cornell.edu/wex/pardon