As a pastor no one every asks me for last minute Father's Day gift. nevertheless, that has never stopped me from offering advice.
The most obvious gift idea: a nice pair nose hair trimming scissors. No dad wants to admit they have out of control nose hair, but it's a truth. Furthermore, even if your dad is losing his head of hair his nose hair will continue to grow with abandon.
Beyond the most obvious. I want to implore you to purchase your father a Brian Doyle book. The title does not matter, just get one. Write on the inside cover how much you love your father, even if it is a troubled and broken relationship, even if you can only write "read this book please."
Brian Doyle was a gifted and talented writer but I think his deep treasure was his ability to make dads, especially, appreciate fatherhood in a deeper capacity. I love my children and I love being their father, but Brian Doyle made me love my children and love being a father even more.