Just charge them and when they plead the “pardon” defense, challenge the validity of the pardons and let higher courts sort it out.
This is not an issue to be timid about. It is the tip of the iceberg and once the effects of Biden’s incompetency is proven, the rest will crumble.
I predict that the Federal Judiciary will not get involved in the pardons, now that Biden says he approved all pardons and commutations.