You are correct about most worms being too small/unrecognizable in poo. You are incorrect about DE and apple cider vinegar in helping keep parasites, worms, and illnesses at bay. DE is ineffective when wet, just like inside animals innards. I've always used ACV in water for my birds and they got worms.
If you're going to worm poultry, use real wormers such as valbazen or safeguard or other wormers as with other livestock.
X2. I already tried mixing DE and ACV in a cup and drinking it when I had worms. I even downed a handful of ground cayenne pepper and was still loaded with worms. Then I ate a whole pumpkin with no success, even though I was confined to the restroom for an entire day.