@telur1 That's where I learned I needed a larger muzzle for my dog. Great group!
He doesn't bite - unless you're a face mask, shopping bag, children's mitten, piece of paper, or anything he could mistake for those. Okay, he doesn't bite those, either. He hoovers them straight into his stomach.
I hate that he needs the muzzle, because then people are afraid of him. He's incredibly social and extroverted, but he gets things down too fast for "drop it", and I just cannot manage to see everything. It would help a lot if people didn't just throw their trash everywhere. He once found most of a cheeseburger in the bushes next to a hiking trail 2 miles from the nearest trailhead. Wtf?
Our other dog came to us an anxious mess with almost no training except being housebroken and trained not to play at almost 8 years old. We've had him close to 3 years now, and he's tons better in spite of a few trainers at the start recommending BE even though he didn't bite at all except the first few attempts at grooming, and then it was the brush he bit. He just wanted to hide behind me or glue himself to my leg. He now loves being brushed, is mostly well mannered on a leash, and will greet new people and get pets if they don't come on too strong - unless they're small children. They're allowed to do anything at all to him, apparently. I don't allow it, but he doesn't care what they do. Like OP's dog, he was always great with other dogs and people who had dogs - and children in any context. It was strangers without dogs that scared him, and only when he was on a leash. The first step was him learning that I would let him walk away from people with a leash on. The next was him getting to meet lots of people off leash at our house where he had a safe place to retreat to. He still needs to be the one to approach, but he's excited to get pets now from everyone, or happy to lie next to my leg if I haven't given him permission yet.
The only thing we're still working on is his really bad separation anxiety from our other dog. He cannot handle being separated unless I'm there with him the whole time. That's really my fault. I thought to work with him on that with me, but not the other dog. It didn't occur to me they would be to be apart, and then i took them to be groomed at the same time. He lost his fluffy mind when he was left in a kennel in the back while the other dog was groomed. We're up to them being able to be groomed, but I can't leave the house with the other dog without him for more than 5 minutes yet unless my husband pets him and sings to him the entire time. My husband can't even walk away on a trail with the other dog. He'll start howling once they're out of sight. I can walk away with him now, but my husband cannot. I swear, he's not our dog. He's our other dog's dog.