Why not get a small chipper and chip non-recyclable plastics into small pieces before dumping?

Because a landfill full of sharp plastic shards is not good for the enviroment. Also given that it won’t speed up the rate decomposition I think it isn’t worth the effort. Add on the power you are going to use to power your chipper and overall it’s probably worsefor the enviroment. It would be better to boycot companies that use plastic packaging.

Yeah it’s not going to help. The pieces are still going to take thousands of years to degrade. Best to not use the products.

They do that at the recycle plants. Not the collection plants, the actual remanufacture plants. They shred the plastic up into little bitty chips, and then melt it and make new plastic products.