I know it costs. But we got rid of chlorofluorocarbons and are preparing to eliminate stuff like coal! This in between.
Proposal: By international agreement get rid of floatable PE, HDPE and PP and the like, for single use small items. If you make bottles and bags of this, you know what happens.
Make that stuff out of PVC and other plastics that sink. As a side effect you sequester that carbon. At the bottom of the ocean with mud over it, it is gone for timescales that worry us.
This would all but wipe out ocean plastic pollution at modest cost. What am I missing?