I think it's a bit daft. There was an item about it on Jeremy Vine earlier, and in some countries people (not just young ones) are given live chickens, rollmop herrings, chipolatas, popcorn and a marijuana joint (not all at once - these were one per country!) as inducements. Some of these would put me off getting it - what would I do with a live chicken?
I can't help thinking that the sort of person who would get vaccinated because of bribes would reject it if he bribe didn't suit them, so it would be counterproductive. If the bribes changed after a while, people would be encouraged to hang on to get the best deal possible.
I would use more of a stick approach, and increase the number of things that can only be done by the double jabbed, but only when everyone has had the chance to get both vaccinations.