High pressure hydrogen is a thing too and regular petrol engines can be converted to run on it. Toyota already did it with an old corolla and a rally Yaris https://mag.toyota.co.uk/restomod-ae86/ https://mag.toyota.co.uk/hydrogen-gr-yaris-showcases-experimental-engine/ so not fully shutting the door but still a big hindrance.
High pressure hydrogen is a thing too and regular petrol engines can be converted to run on it. Toyota already did it with an old corolla and a rally Yaris https://mag.toyota.co.uk/restomod-ae86/ https://mag.toyota.co.uk/hydrogen-gr-yaris-showcases-experimental-engine/ so not fully shutting the door but still a big hindrance.