> Except in the world of "anything is possible," mirror life would have no food. All biomolecules are chiral.

Many essential biomolecules, nutrients, and amino acides are achiral (e.g. carbon dioxide, water, ammonium, phosphate, sulfate, glycine, and more). Mirror organisms could easily - at least in the realm of plausibility - function as autotrophs to convert sunlight, CO2, etc. into organic sugars, or extract energy from inorganic materials like hydrogen or iron paired with CO2.