Please don't pin a puppy - or any dog.
Your pup sounds normal.
You can get some relief if you'll exercise ( not just let him out) throwing a ball, going for walks etc..
Also important to stimulate his mind. Hide a treat or favorite toy and teach him to search for it.
Get some treats and teach basic commands like sit, down, come etc..
He'll grow out of the mouthing and be better behaved.
These guys take work to form them into an obedient companion.
Nothing is as simple as it seems or as complicated as we make it~
Attitude is everything -- Pick a good one!
Sofie AKA Ussina vom Haus Brezel
Jack von Jagenstadt
Tatty - Burmese bad cat