Polyurethane is made by (among other steps) mixing paint thinner and phosgene gas. It’s a nasty dangerous process.

The only time plants are involved is when they mix in some fiber pulp at the end.

Plant based plastics exist, but they are not polyurethane.

I got burglarized and they left a significant amount of cash in foreign currency that was sitting out in the open from a recent trip, because they had no idea what it was. Nobody is stealing rackmount equipment.