Not exactly answering your dilemma, but I was watching a cooking channel yesterday (Sorted), and they were talking about seaweed - it’s wild (heh). You can use it to make straws, bags, packaging and all sorts of stuff that’s foodsafe and biodegradable. And apparently, even if we replaced all the plastic used for that kind of thing with seaweed, we’d barely make a dent in the ocean’s seaweed supply - we’d use less than 1% of it.