This is interesting. There's a related "startup" tackling the problem from a different angle: https://theoceancleanup.com/
They did some research and found that something like the top 5 or top 10 rivers in the world are the source of 80+% of the plastic in the ocean. So they came up with this plastic-filtering-barge design with hopes of placing them at key points in all the major rivers. So far four are built and in operation. Absolutely not a solution but a ton of harm reduction.