GeoDirectory Multisite content sharing/aggregation

I realise this is a customisation but wanted to run it past you for comments as to feasibility and on how to specify it.

We have a website https://goodlocalevents.com which is currently standalone. It is largely GD with WC Bookings enabling booking functionality.

I have a number of cities who want their own similar standalone site with similar functionality to promote and allow bookings for their parks and open spaces — but just for their own local area. They want their own domain and will generate their own content.

My idea is we set up a WordPress Multisite where they each have their local site which can have its own domain or be at, say, timbuktu.goodlocally.com. We maintain the infrastructure and give them up identical CPTs within GD and some system for aggregating content from their local sites into a the goodlocally.com central site which lists all the events and venues.

My particular questions are
1) is this going to be difficult to achieve?
2) do we have to export the data (and can this be done)? or,
3) given this is a multisite setup could we tap into the data for the sub-site listing and aggregate it into the main site from the database so as not to have to maintain, correct and update multiple identical entries?