What's the most sustainable packaging for beauty and personal care?

It depends on the product. For liquids and refills, recyclable mono-material PE pouches with up to ~70% post-consumer recycled content (GRS certified) are the defensible choice. For dry beauty, powders, bath salts, masks up to 1kg, certified home or industrially compostable laminates open up. Every option comes with verified carbon and end-of-life data so the claim on your pack survives scrutiny.