Aggressive sleeping puppy

Hello

Any advice would be so appreciated. I adopted a puppy 1 month ago. I have raised a few dogs now but this one has some challenges. He is a pointer mix but small only 20 lbs and just turned 6 months old.

Archie is going for puppy training but not for 3 weeks. My biggest concern and what I have no idea how to handle is some aggression he shows when overly tired or sleeping. Overall he is a cuddle bug and sweet as can be but super hyperactive lol. He lived in a shelter his entire puppy life.

When he is sleeping or curled up and comfy and falling asleep he shows aggression if moved. Sometimes he will lay in a spot and fall asleep where he cant be or needs to move over. Example he is curled on the bed or couch but has to move over to make room for his human ( I know lots of people will say he shouldn't sleep on the bed or couch but that doesn't fix this problem). Another example when he is playing with my 13 year old niece and bouncing off the walls she goes to make him sit in place longer then he wants or plays more then he wants when he is super hyper and bouncing around like a fool, he will growl or snap at her. More so with her then anyone else. I watch them she isn't rough but she does play with him on the floor and picks him up a lot. There are rare moments that he will growl and get serious. From the past few times we know to freeze because if you don't the next thing to come is an aggressive jump up and snap at you aggressively. He has never made contact but I am guessing that comes next. This has not been something that has happened daily. It happens randomly and normally when he is overstimulated with lots of people or excitement or exhausted and sleeping. How do I stop this???? I am so scared he will grow up aggressive. Like I said I will be starting puppy classes in 3 weeks but any advice now would be helpful. Also this is not a behavior that will be easy to recreate in a puppy class or during a training session.