You and @alberto are both raising excellent points. I think the only way to approach this is to start at the very foundational level, which is to organize this part of our lives exactly like all the other big societal areas: By moderating and navigating the various (and often conflicting) interests through democratic means - in other words: introducing transparency, accountability and democratic oversight. Currently, smart city projects are often ushered in through the back door of public procurement in processes so obscure and opaque as to be essentially free from meaningful oversight.
This is where the question of metrics later should be decided (but currently we don’t have the policies in place to make that possible) and where we can decided collectively which aspects of health impact should be studied…