I have always integrated a SAML IDP with Salesforce and I'm trying OIDC now.
I have created a Salesforce OIDC app in my IDP. I took the clientID and clientSecret, and then created a Auth. Provider in Salesforce. I copied the Callback URL and SSO URL back to my IDP.
But my tests both with Test-Only Initialization URL and SSO from my IDP are not working.