How to get end user to select their own API-based info

I’m building a tool where I’d like the end user to be able to select from certain parameter that come through specific APIs to show certain results.

I know how to set up a backend API connector, but is it possible to allow the end user to plug in their own platform (example: Google Analytics) data? Is is through a user authentication for every platform that needs to access the API?

Thanks in advance!

David