My local hospital uses Epic’s MyChart, which should implement the standard FHIR API. How can I authenticate and access my data through a script? There are a million websites like https://onerecord.com/ that let you log into basically any patient portal by searching for the name of your hospital and giving you a little pop up to login through. How do I actually implement something like this?

I found tutorials on using the FHIR API but I can’t find any explanation of how these health data aggregation websites like OneRecord find and authenticate with different hospital’s FHIR API endpoints.