I hope I don't have to ask this in Sweden, I would not want to come across as incredibly rude.
It isn't always rude. What if he got into a car accident or something? Asking this question would imply that you are concerned/worried about him.
Then I'd go for something a little softer, like "Is your grandpa okay?" instead of "lmao he dead, right mate?"
"Is your grandfather alive?" sounds pretty soft to me
Not a great conversation starter..
Does this literally translate as "Does your grandfather live?"
Yeah, pretty much. If you translate "is your grandfather alive?" directly, you would get "är din farfar vid liv?" but it's less common and a bit archaic.
I believe it also works for "is your grandfather living", which would be a bit closer to a standard English construction.
Min farfar inte lever, men mina barnbarns farfar lever.
Min farfar lever inte*
Seems to be a little bug: I answered "is your grandfather alive", and duolingo answered:"Another translation: is your grandfather alive"
You might have made a typo
Does swedish not use 'is' at all?
It does, just not here. This sentence actually literally translates to "Does your grandfather live?"