Preheat the oven to 300°F (150°C). Adjust a rack to the lowest part of the oven. Lay a piece of parchment paper on a clean part of the counter.
In a large bowl, combine the pepitas, sunflower seeds, flaxseed, flaxseed meal, sesame seeds, almond flour, hemp hearts, psyllium powder, and 1½ teaspoons salt. Mix in the coconut oil and boiling water to form a somewhat gelatinous dough ball.
Scoop the dough out onto the prepared parchment paper. Cover it with a second piece of parchment and use your hands and a rolling pin to evenly flatten the dough into a 6-inch by 12-inch rectangle.
Slide the dough and the top and bottom paper onto a baking sheet. Peel off and discard the top layer of parchment, then bake the crackers on the parchment until somewhat firm and golden around the edges, about 30 minutes.
Remove the crackers from the oven, use a pizza cutter or knife to slice the giant cracker into 32 (1-1/2 -inch) squares, then continue baking until crisp, another 20 to 25 minutes. Turn off the oven, then leave the crackers inside to thoroughly dry, 3 hours. Enjoy!