Thank you for your reply. I will review your suggestion and let you know, but it may take a while :-)
Looking at your question basically what you want is SSO authentication for exposed rest api by your mendix application.
To achieve this you should add OIDC SSO marketplace module into your application and configure it as per your Idp.
You can go through this detail document of how to configure this module → https://docs.mendix.com/appstore/modules/oidc/
Once you have configured OIDC module then you need to change authentication method of your expose api to custom and select OIDC.APIAuthentication microflow which has HTTPRequest as the input and returns System.User as the output.
So basically whenever user will try to consume your application exposed rest api then authentication will take place in APIAuthentication microflow.
All the best, I hope it helps.
Hello Joshi, thank you for this information!
API authorization works well with the OIDC module. We use the external app's IDP, which can use the Mendix REST service with its id_token in the header of the http request.