Bill is not a felon in West Sconsin. It would depend on the specific law regarding felons serving as policemen if a felony committed in another jurisdiction prohibits them from serving.
Similarly, the word “pardon” means different things in different jurisdictions. In some jurisdictions it makes the conviction legally void (i.e. it never happened), in others it restores privileges that the conviction has taken away (i.e. you are still legally a convicted felon but the legal consequences of that status are suspended. Notwithstanding, the government of West Sconsin cannot pardon a conviction in another jurisdiction. Each jurisdiction is sovereign.