Kadi, congrats on your efforts.I agree with Al, I'd spend a little more time bonding with him. Then I'd do like Jeff suggested. Work focus at home, in a calm non-distracting environment. Like you are doing, with the dog in front, but also with the dog in heel. I like my dog to know how to give focus sitting in front, sitting in heel, and standing in heel, before I start doing any actual watching. Once he gives you good solid focus without distraction, then start adding simple distractions. Such as someone walking around. Or clapping, dropping something, talking, etc. Also, once you know the dog has a solid understanding of "look" or whatever your focus command is, you can start to introduce some minor corrections for looking away. Slowly just increase the level of distraction. I use food at first for the reward, since it's a quick/easy reward and we can keep working while rewarding. Later I use a toy. And after that I use the decoy. IMO a dog who lives for the bite, is great to do focus work with, since they have something they are VERY motivated for. If you require them to focus on you, to get the bite, they will very quickly be giving you strong, pushy focus, waiting for that release.
I heard the same thing, "if you can do that with this dog it will be a miracle", when I got Mac. Mac now focus on me for all sends in bitework, gives focus during the heeling, gives focus with a decoy standing 15 feet away jumping up and down, rattling the stick, etc. It's not 100% yet, sometimes he gets stupid then you see him remember "oh, I have to look if I want X" but he's getting there. He's already doing more than I was told I'd ever be able to get from him