I agree with the others. You can always hope for the best, but if you go into this with the expectation that they will be friends, or even that they will be able to coexist peacefully without a barrier between them, I think you might be setting yourself up for disappointment. They’re prey and predator, nothing about their relationship will be easy, unfortunately. We just got a puppy a few months ago. He’s a GSP, so he will be similar in size to your pup. He is 7.5 months old now, weighing a bit over 40 lbs. There is no way in hell I would put him in a room with our rabbit, even if he was on a leash. He’s way too hyper, too big, too strong. One play bow at the wrong place, at the wrong time, and the bun’s spine would be crushed. We have two cats that he has been face to face with since we got him. He’s still having a hard time being calm around them. 30% of the time he’s fine, 70% of the time he goes bananas as soon as they show up and starts throwing puppy punches.
He spends a lot of time in the kitchen, which is adjacent to our bun’s room, they are separated by a baby gate. He can smell and see the bun, and he’s never gotten very excited about him. But I know that if the baby gate wasn’t there, he would lose it. I don’t expect to be able to let them meet face to face for a good while. First he has to get through the worst of his puppy craziness, and his obedience has to improve A LOT. It might take another year, maybe even two. Maybe I will never feel comfortable enough to try it, but that’s okay, as long as everyone stays safe.
Just take it slow, they might become friends, but sadly there are no guarantees.