Boy do i feel your pain on this one. Our girl Roane was a tough train too. although we knew this was a breed trait going into it. I use to say that she was beautifully trainned until she thought she had better idea than mom😏

dont beat yourself up its frustrating but one day the light bulb will come on and totem will take your "suggestion" until then lots of repetition. Does he like treats or toys? We did alot of recall trainning with a very long leash and treats. Small bites, anything is a win when there young. Short session are good at that age, if either of you are frustrated you can come back to it later. 

First, have you given yourself permission to grieve for the loss of Totem's limb and the future you had imagined with him?  All of your hopes and dreams for this puppy were crushed because of your neighbors unsocialized dogs.  It is normal and healthy to grieve all the could have beens and should have beens. This has been such an intense experience for you when all you wanted was a friendly little dog.  You never asked for a special needs dog and it is so normal to be feeling tired and overwhelmed by this because it is tiring and it is overwhelming.  Please give yourself permission to not be OK.

Second, what does Totem need to know right now?  There are only two critical skills he needs in life right now at his age.  Bite inhibition for people and dogs and he needs to learn to be friendly with all types of people including screaming children, men, people wearing hats, riding bicycles, people who are unsure of dogs, that people are great even if they trim their nails or hug them.  Little dogs tend to be much better at hugging and handling than larger dogs but not always.  Since the amputation was rather invasive, he's either going to be a pro at being handled by the vet or absolutely hate it.  

Can he mouth your hands and not hurt you?  It sounds like when he meets a dog the right age and size, he has a great time with them and plays really well so I think you're doing fine there.  The human socialization part is tricky  under the best of circumstances and during COVID it is really, really hard.  I just lost my greyhound Will who was 94 lbs of LOVE and he was so lonely the last few months of his life because almost no one would pet him at the park during covid.  I even got a 9 foot leash so we could keep our 6 feet apart.  Just my immediate neighbors would say hi but we live in a town of 520 people with one stoplight and those hellos were few and far between.

The other skills that he needs to fit into the human world can just happen organically around the house - what to chew, where to eliminate, where to dig, when to bark, how to walk nicely on leash, and how to greet people.  Recalls tend to be tough with scent and sight hounds.  They can be done but the selective hearing is legendary.  They can hear you opening up a bag of cookies from across the house with a football game blaring but somehow just can't hear you when no one else is home, all the tvs are off, and you're 10 feet away.  With puppies, lure and reward tends to be the best way to train them.  Super high value treats given out randomly can help train a recall in such an independent dog.  Or train it on leash with lower value treats.

I used to do "Nothing in Life is Free" training.  Eventually I moved to relationship based training.  Relationship based training still has strict rules but we also believe that Plenty in Life is Free.  My dog is allowed to have my affection simply because they're cute.  I also allow rules to become less and less after a dog hits 10 and if they make it 13, well there are no rules for the dog as long as we're not violating safety.  All of this backfired with Will because he came into my life when my other dog was over 10.  I'm kind of grateful that he pushed back on the rules cause he didn't make it to 10 but that's just me being human and trying to rationalize it. 

One more Titan story. You and your husband do not sound like this family so please don't think I am comparing you to them.   This was an extreme case and the family continued to stick to extreme choices. Once all the drains came out of Titan and the stitches came out, his family felt so overwhelmingly guilty that this happened to their puppy that they just decided to not train him at all and let him do whatever he wanted to do.  I'm not sure when they had to call in the Behaviorist that I used to work under but their little miracle puppy had become a demon dog.  After a couple of months with the behavorist, it became clear that Titan needed to be rehomed.  One of the other dog traininers who worked under Molly took him in.  He eventually became a good therapy dog....eventually...but he was always testing boundaries with everyone but the people he did pet assisted therapy with.  He actually was a great reading assistance dog and enjoyed having kids read books to him.   He also would allow himself to be dressed up as the Grinch at Christmas and wore a green and red fursuit with pants.  I don't know if I have any pictures of that now but it was hilarious.  

Totem sounds like a great dog though and you're doing amazing considering all the hoops you have had to jump through mentally and physically.  Please, please give yourself a pat on the back.