Preheat the oven to 350 degrees F.
Fit a baking sheet with a cooling rack and spray the rack with canola spray. Spread the pineapple rings out on the rack, transfer to the oven and bake until the rings are lightly browned at the edges.
Meanwhile, combine the oats, flaxseed, sunflower seeds, walnuts, cinnamon and salt in a large bowl and toss well to combine. Pour the mixture onto a baking sheet and transfer to the oven for 15 to 20 minutes.
While the oats and pineapple rings are baking, combine the honey, pineapple juice, molasses, confectioners' sugar, almond extract and a pinch of salt in a small saucepan. Bring to a simmer over medium heat and cook until the mixture coats the back of a spoon, 10 to 15 minutes.
Spray an 8-by-8-inch baking dish with canola spray. Combine the oat mixture and the honey syrup in a large bowl. Chop the pineapple rings and add them to the bowl. Stir well to combine. Pour the entire mixture into the prepared baking dish and spread to an even thickness with the back of a spoon. Freeze for 30 minutes, then cut into bars.