20" is worth the length and weight for hunting. If you want an hbar and don't like weight, flute it to keep your balance proper.

Rifle length gas system and recoil buffer.

0.750" gas block, keep the weight near you.

1:8" or 1:9" twist in case you do decide to shoot longer ranges with heavier, slower bullets.

Collapsible stocks of GOOD MANUFACTURE are fine for hunting, but you may not fit the cheek weld well, especially for a scoped rifle. You will honestly never for one second need a collapsible stock for any purpose.

An AR-15 in .223rem is not a deer rifle. I won't waste my time arguing it with you if you believe otherwise. Just because a 16oz hammer can drive a railroad spike, that doesn't make it the proper tool for that job.

50-55grn bullets out of a .223rem seem to be the ideal weight for predators, in my experience.

Vertical foregrip isn't really functional for a semi-auto hunting AR. If you want one, but one, but it doesn't really serve much purpose on a semiauto hunting rig. It's just extra weight.