I tead a few months ago a very educative article from a French researcher who demonstrated that H2 does not decarbonise at the moment ( create more CO2 than it saves under current and near future production methods) and so cannot be used for the "net" zero deadline of 2050. He also mentioned the impractibilities to use this for aircraft for the very same reasons explained here already , mainly size and weight of tanks, not to mention certification which is likely to take many years. VTOL prototypes with 30min autonomy for 4 pax maybe but not for carrying 100-200 pax over long distances. Electric with new generation batteries (not Lithium) with less weight and longer capacity ,and with fast recharges cycles is most probably the way it will go for aviation .
The recent news coming out about how the "Titan" subsersible lost over the Titanic was built , operated and (never) certified will most probably remind our regulators that there is a big difference between encouraging innovation , buiding prototypes and proposing safe transportation of paying passengers .