The Fasten Sources is a library that defines medical provider metadata (definitions - OpenID Metadata documents) and http clients (OAuth2/Smart-on-FHIR clients) which can be used to retrieve data from various Medical Providers (clients).
MSK
cityMD
Lennox Hill (especially west village)
goHealth
Northwell system (Lennox Hill)
GoHealth, CityMD, Lennox Health,
HSS | Hospital for Special Surgery
OneMedical
NYC Health + Hospitals
Goldman Google have their own ER systems. Premise Health - https://www.practicelink.com/facility/premise-health-foster-city-ca/premise-health/