Combine all of the ingredients in the chickwheat loaf except the vital wheat gluten and blend using a high speed blender until completely combined. It will be the consistency of a medium-thick batter.
Pour the mixture into a bowl, being sure to scrape out the inside of the blender cup, and add the vital wheat gluten. Stir to combine, then use your hands to kneed the dough for ~2 minutes to fully combine. Let sit for about 10-15 minutes for the gluten to absorb.
Take half of the chickwheat dough and put it in the bowl of your food processor and process for about 5-8 minutes. If you don't have a food processor, you can use the dough hook of a standing mixer but you won't get quite the same texture. You can't replace this with hand-kneeding - it won't get the same texture at all. While the dough is in the food processor or mixer, it will become very stretchy and stringy - you'll know it's almost ready when you see little 'strings' of the dough sticking to the sides of the food processor bowl. If your food processor is anything like mine, it will get quite hot, and because the dough gets so sticky, it will take a few minutes to scoop all of the dough out. Clear out your food processor, clean off the blade, then repeat with the second half of the dough (the only reason not to do them both together is it will be too much resistance and burn out most home food processors).
Once you've fully processed both halves of the chickwheat dough, kneed them back together and pat into a roughly rectangular shape. Wrap the square very tightly in tin foil - I recommend using 4 or 5 layers. This will create additional pressure and texture when you cook it in the next step.
Add two cups of water to your Instant Pot, or enough to cover the base but not reach the bottom of a trivet or stand. Place the foil-wrapped chickwheat dough on the trivet, then seal the Instant Pot.
Set the pressure cooker on manual and cook for 120 minutes.
Quick release the pressure, and remove the chickwheat loaf. The foil may have split as the loaf expanded - don't worry, it will still be fine. Let the loaf cool, then remove the foil. Once it's fully cooled to room temperature, you can use it immediately in the gyros, or put it in the fridge for up to 3 days. It makes enough to use in other recipes as well, so be sure to save the leftovers and check out other meals using chickwheat.