Use Case 1:
It would be really nice to be able to, for example, pull in data from another wordpress website via the REST API – that way if we have an ecosystem of websites on various domains / sub-domains, that we could build views for all of them on one dedicated site.

Use Case 2:
Google Sheets – pull in data from a linked google sheet

Use Case 3:
Google Analytics – pull in data from your google analytics account to build analytics dashboard