Meliora
Meliora is about as plastic-free as a detergent brand gets, and vocal about it: its laundry powder ships in a paper-and-steel canister with a stainless scoop, refills come in paper, and the company publicly campaigns against PVA - it has a "PVA is plastic" explainer arguing that dissolvable sheets and pods are plastic film. The formulas are short lists of minerals and vegetable soap rather than synthetic-surfactant blends, which is the one honest tradeoff: soap-based cleaning can underperform in very hard water.
How clear are their specs?
Publishes full ingredient lists, MADE SAFE certification, and takes an explicit public position on PVA/plastic.