Oh my goodness! I've been having computer issues and all missed this. I knew Jackson wasn't feeling well, but I didn't know he was diagnosed with pancreatitis.
I'm so glad to hear Jackson is home, and you are adjusting as well as you can at this point! Just take everything slow, and I have no doubts you'll find a food that works well for Jackson that you can live with.
As far as training, you could always train him with pieces of the kibble you decide upon. I'm not sure if even veggies and fruits will be no-nos now, but, if not, Rory and Lane love frozen green beans for treats, along with other raw veggies and fruits (I know you know all the ones that are toxic to pups). Costco has giant bags of organic frozen green beans that can be cooked if you prefer. Maybe you can find something like that will work. I've also heard of people baking the dog food into treats, etc, so where there is a will there is a way - no way you will have to stop training Jackson - I know how much you both enjoy it!
It's so hot out right now it's probably good that he needs to take it easy for a few days.
I hope he has a great recheck, and you can discuss some of your concerns with the vet!