We have set up ADFS with AWS and are able to log in via a link to the idpInitiatedLogin as described in here (and other places):
The URL to the idpInitiatedLogin takes some options, like which backend to use, whether to force a password login etc. that are handled at the ADFS layer before the request is redirected to AWS.
Is it possible to supply additional parameters to the login call so that instead of choosing a list of roles and accounts you can supply them as parameters to the login call?