Ukraine and its allies should reverse engineer the V1 flying bomb

No need to reinvent the wheel. The V1 is proven technology. It would also give the Ukrainians a weapon equivalent to the Russian Kinzhal air-launched cruise missile. 

For better results, replace the warhead with cluster or incendiary munitions. 

The positive impact on Ukrainian morale would be huge, especially if civilians were put to work making them. Perhaps even a deal could be struck whereby Ukrainian men who fled abroad could be welcomed back if they agreed to work in missile factories.