Whether the preference to vote in your State is for in-person, mail-in, or a combination, that should have no bearing on what the preference is in another State. Each State will enact legislation appropriate for that State.
If your State has been in-person for decades, and the Governor decides mail-in ballots will be sent to ALL registered voters, without any legislative review, and contrary to the State's constitution, then we have a problem. Again, that is a problem that impacts only that State. no other State.
We do not need voting process (in-person, mail-in, or a combination) to be nationally specified, but verification of one's right to vote, that is at least worth the discussion.