About that "accepting a pardon means confession of guilt" thing -- yeah, not so much.

[sharedvalues]

6. This is complex constitutional law

Here we should defer to constitutional lawyers.

Larry Tribe (top constitutional lawyer) says

Link to tweet

"So 5th Amendment privilege might remain wrt state incrimination, but it might be wiped out by the admission of guilt in accepting a pardon."

And Volokh is a good source, an academic expert though not someone who has argued many cases before SCOTUS.
"fourth-most cited legal scholar by appellate courts between 2010-2014, Volokh teaches free speech law, tort law, religious freedom law, church-state relations law and a First Amendment amicus brief clinic. Before coming to UCLA, he clerked for Justice Sandra Day O'Connor on the U.S. Supreme Court and for Judge Alex Kozinski on the U.S. Court of Appeals for the Ninth Circuit."

This question will be decided by SCOTUS.