My dad died early in 2020.
I looked up his voter registration online and he was registered republican.
I emailed the county election official where he lived and asked if he had cast a vote in the 2020 presidential election.
The official said no.
I have no way to check if that was actually true.
But I did offer proof of death and asked them to cancel his registration. They said they cancelled it.
So at least Dad's vote will not be used in a future election.