Every few years someone is faced with the task of integrating a Meteor application into an environment where the user logins are handled using SAML, see for example SAML in Meteor in 2022
Last year I was faced with this task. The result is the Meteor package qnipp:meteor-accounts-saml.
There is a demo application at https://meteor-saml-demo.meteorapp.com/ (Thanks to Meteor for providing this free opportunity again).
The source code for the application and the package can be found at GitHub - qnipp/meteor-saml-demo: SAML integration for Meteor.
The package has now been in productive use for several months. I have not heard any complaints from customers.
All the best with it!