I had a friend with a dog like yours
Although I didn't see the dog as a puppy, I did see it full grown and it looked just like yours. It wasn't tiny at all, but did have quite a bit of hair, like yours!
I would say yes, it's purebred. And if the dog is not, that's ok too! I sometimes think a "not so purebred" is much more likely to have a healthy, long life, compared to the oh so fancy purebreds. It's the gene pool that's important!
Your doggie looks like a barrel of fun as well as a cuddle bug. Fritz, my friend's doggie was both of those things to his family. He lived a long and happy life. We all miss him.