Once, a couple of years ago, I had a job at chemical company. They produced additives, stuff you add to, e.g., plastics to improve certain characteristics. One thing they experimented with was additives that helped to break down plastics into molecules you also find naturally. In my best layman's term, below micro-plastics and something that is found in the environment anyway and will just become part of the natural cycle. In tests, they managed to achieve that (based on legal limits for plastics in soil samples, within a year in the ground. meaning, any plastic concentrations dropped below legal limits and detectability. Quite nice. Not sure what happened to that, being a new product it wasn't cheap to produce (yet). Not sure if it was even suitable for most use cases.