@jesusrwaldron He's probably not actually teething yet, but just being super mouthy. GSDs are prone to that. I tried a
ton of chews and the benebone that I can't find anywhere was a popular non-edible one. He's enjoyed bully sticks (although I'm still seeing if they are going to eventually agree with his tummy and had to get a holder cos he tried to swallow all six inches) and yak chews (sadly those break on the tile though so those are an office only treat). I've had good luck with frozen carrots, ice cubes, and rope toys. Split elk antler had a good go for a while too. Pretty much anything not your hand that you put in their mouth is a good redirect if it's a toy.
The mouthy biting isn't going to stop until he knows that's not what he should do though. He's probably trying to initiate play, so the best I found was to just stop engaging with him AT ALL when he bites me. It took a while and patience, but I'd do the reverse time out thing where I'd leave him and go out of sight for at least 30 seconds (or if not possible, turn around and cross my arms, being as unfun as possible) and then come back and try again. Usually I'd have to repeat this a few times, because he's a stubborn butt. It has made a huge difference and sometimes he still gets a little mouthy but for the most part he's improved a lot.
What's also helped is spending time with my parent's 3yr old GSD who worked on his bite inhibition (which means he doesn't bite as HARD now, which thank god). It's really difficult as a human to convey, no don't bite me so hard. And honestly that yelping thing didn't do jack shit for me and he just licked the apple spray off, so your mileage may vary.
