Just to state one aspect of this, since I don't think you said it explicitly. Alternative plastics currently are generally not as efficient to produce as mainli

Just to state one aspect of this, since I don't think you said it explicitly. Alternative plastics currently are generally not as efficient to produce as mainline plastics, IE they consume more energy. If that energy consumption is connected to fossil fuels, it could be a step backwards to implement such a process at Lego scale. There's also another aspect of, if the demand of global oil used for plastics goes down, it could be more appealing to burn oil for energy, if the price goes down accordingly. There's some argument to be made that while we spin down the oil industry we should be making more fossil fuel based plastics, to be entombed in the earth somewhat like nuclear waste. I say all this unhappily as someone who really wants our species to make forward progress on climate and resource policy.