Heat large skillet over medium-high heat. Add pork sausage (or ground turkey thigh), thyme or rosemary and 1/2 to 3/4 teaspoon sea salt (use 1/2 tsp for 1/2 lb meat and 3/4 tsp for 3/4 lb meat). Cook, breaking up meat with a spatula, until all pink is gone, about 8 to 10 minutes. Remove meat with a slotted spoon to a bowl to fully cool.
Preheat oven to 400 degrees Fahrenheit. Line a cookie sheet with parchment paper. Set aside.
Combine cold water and apple cider vinegar in a Pyrex-style measuring cup. Set aside (or place into fridge).
In large bowl, whisk together dry ingredients: cassava flour, tiger nut flour, collagen, 1/2 teaspoon sea salt and baking soda. Set aside.
Cut cold fat into flour using pastry cutter or food processor. Cut fat or pulse to combine until largest fat pieces are smaller than pea-size (and all loose flour is integrated into the fat).
Pour water and ACV into flour mixture, and stir (with a fork if using a bowl) or pulse to just combine. Do not over-mix.
Dump half of the dough out onto parchment lined cookie sheet. Loosely form into a 1-inch thick (about) rough square or rectangle. Do not pat it down. Add cooled meat, spreading out pieces evenly. Dump second half of dough on top of meat. Spread out top biscuit dough evenly. (See process photos in Recipe Notes section below.)
Use your hands and the back of a spoon to gently push together jagged pieces, first from the sides, and then (don't push down hard) from the top. (See process photos in Recipe Notes section below.)
Use a sharp, long knife dipped in cassava flour to cut straight down into dough. (This dough will make 6 or 9 biscuits, depending on whether you create a rectangle or square of dough.) Dip knife in flour after each cut, until you have all biscuits cut. Spread out biscuits just slightly from each other, so they have room to cook and expand slightly. (See process photos in Recipe Notes section below.)
Bake in preheated oven 25 minutes, then pull out briefly to rotate. If the biscuits have baked into each other, cut them apart, then rotate each one, so inside pieces are faced to the outside of the pan, to darken evenly. Return to oven and bake an additional 10 minutes.