In case you want to make your own if supply issues continue, I use the
Post Punk Kitchen recipe, which is Italian (it has fennel seeds and hot pepper flakes), but I bet you could adjust the spices to whatever you like. They are a little labor-intensive, but they are so worth it, IMHO. Each recipe makes 4 large sausages, and I typically eat half at a time. I always make three batches or so and then freeze them. They keep great!
Tonight I am having acorn squash stuffed with a mix of wild rice, seitan sausage, Granny Smith apples, walnuts and dried cranberries. I put some cinnamon in and a dash of nutmeg along with a pinch of sea salt and some pepper. The stuffing would also be great cold on a bed of lettuce. I have enough for several meals.
Your sandwich sounds great!!