Access third party App on behalf of user through SSO/OAuth

[Marvin_Wenzel]

Hello.

I develop a JiraDC Plugin. In it, I wish to access and use a third party's REST API identified and authenticated as an End User clicking one of our buttons from within JiraDC.

Both the third party app and JiraDC are configured to offer login with the same SSO/IdP solution - Microsoft Entra.

When researching, I only found an article on the topic of accessing Jira from the outside using 3LO, not the other way around. (https://developer.atlassian.com/cloud/jira/service-desk/oauth-2-authorization-code-grants-3lo-for-apps/)

1. Does the Atlassian API offer any assistance/framework for accessing third party services on SSO-authenticated as the JiraDC user?
2. Does a common or best practice exist for this?

Thanks a lot for your assistance in advance.