Would be great to see similar tools for other cities!
And how easy would it be to make this work for any city?
In principle it should be possible to do the same for any city. The hardest part is getting the data and massaging it into shape, which can be somewhat tedious. London is a fairly "easy" city for this due to the large amount of open data that's readily available from the ONS and the like.
You mentioned that massaging the data into shape as one of the problems, which I think is possibly one of the best applications of LLMs in my opinion. Creating a pipeline of a data feed (still hard) into an LLM which outputs JSON with the fields of interest would be amazing.