Cut the bacon into ½-inch chunks (kitchen sheers or scissors make this easier). Cook in a small to medium saucepan over medium heat until thoroughly cooked but not completely crispy.
Remove the bacon from the pan and set it aside atop some paper towels to drain. Discard (or save for later) all the bacon fat except about a tablespoon worth.
Add the onion, shallot, and sweetener. Sauté over medium-low heat, stirring frequently, until the onions are golden brown and caramelized.
Add the garlic and sauté another 2 minutes or until the garlic is lightly toasted.
Return the bacon to the pan. Add the remaining ingredients except the xanthan gum and stir together.
Allow to simmer over low heat, stirring occasionally, until the liquid has reduced by half (about 30 minutes, give or take).
Remove from the heat. If the jam isn't as thick as you'd like it to be, dust the xanthan gum over the top then stir it in.
Store in an airtight container in the fridge. Heat before using.