I think people forget that if you process something enough it’s not biodegradable anymore.
Like there is this biodegradable glitter made from seaweed. And they check it’s genuinely is. But the amount of processing that goes into turning it into glitter is too much for it to remain biodegradable. It’s just glitter with extra steps. Maybe a little better at the start (no oil based plastic) but the end result is the same.
So when someone says “oh it’s WOOD based” and it looks like plastic. It’s plastic. It might have started as wood, but it’s plastic now. Same with all those “alternative materials” such as fungi(?) based, plant based, etc.
So if someone’s promising “100% plant based not plastic” and it looks a little too much like plastic… don’t fall for it. It’s still plastic.
Obviously this excludes stuff that is obviously not plastic. Such as a wooden tooth brush, glass, recycled plastic is still plastic but at least they admit it and are reusing it, Cotten, linen, heshen, other genuinely biodegradable materials etc.