How does one embed data such as a rating / review from other sites into an App?

I am not at all familiar with swift or iOS developmet (I only have python / SQL experience) so I am sorry if this is a stupid question.

How do iOS developers embed specific data such as a rating or review from other sites into an app that would hypothetically gather this data from several different websites?

So for example, for video game reviews app, the app wants to have the rating or review number from different sites that are all built and formatted completely differently, how does the iOS dev pull this specific data into a SQL table or into the iOS app itself? I imagine that the iOS app would talk to SQL first, but how does the link between the sites and the back-end environment connect?

How have you implemented this before, or how have you seen / heard of this being implemented?

Can this be done without scraping / hurting SEO?