You don't have to be charged with a crime to be pardoned for a crime. But you are basically agreeing that you have acted in an illegal way. Nixon, for example, was never charged. Another famous example of just blanket pardoning an entire group of people who engaged in many crimes was Lincoln's pardon of Confederate soldiers. It didn't include specific acts, but basically said that if you were an enlisted man, you're free and clear. I somewhat expected the president to do the same for the Capitol terrorists, but I don't think he will now. I think he will try to blame them as a way of saving his own skin. Pardoning them at this point would show that he's sympathetic. And we all know he will throw anyone, including Don Jr, under the bus to save his own skin.

The state prosecutions for crimes that have been pardoned will get sticky, because I believe you can't be tried on state crimes that are indistinguishable from federal crimes for which you've already been tried. It's a special circumstance of double jeopardy. The state charge has to be different enough to not look like being tried twice for the same act. How a pardon might complicate that is well beyond my knowledge.