Would you let one or two cities have veto power over the policy of an entire country? If not then what's the difference here? If yes do you think that would work?
Of course the important thing is to decide what should be handled at the city, region, nation and EU level. There's a tradeoff. Decisions made at lower levels are generally better for accountability and give better adaptability to local circumstances but on the other hand they often lose leverage.
A city wouldn't be able to talk as an equal to large companies like Apple and Google for example, even many countries can't. But the EU can. Replace Apple / Google by Russia / China / US and it's even worse.
Of course the important thing is to decide what should be handled at the city, region, nation and EU level. There's a tradeoff. Decisions made at lower levels are generally better for accountability and give better adaptability to local circumstances but on the other hand they often lose leverage.
A city wouldn't be able to talk as an equal to large companies like Apple and Google for example, even many countries can't. But the EU can. Replace Apple / Google by Russia / China / US and it's even worse.