Somewhat yes and yes. Demons can hunt and eat other demons in order to gain the “energy” others demons have generated from the human souls they’ve devoured. It’s more profitable than eating humans souls, but it’s also more dangerous because the situation can turn sideways rather quickly with the predator becoming the prey.
As a half-demon, the MC can “eat” their fellow demons and grow from their power. At that point, the MC isn’t eating human souls, but rather the “energy” that the demon has generated from those souls; the souls, at that point in the digestion, are “gone” - no longer are they the identity of that individual - but rather just “energy”.