@Robert Busch ,
Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question.
What I understand from your question is that you want to use the Azure Active Directory (Azure AD) B2B collaboration feature within External Identities that lets you invite guest users to collaborate with your organization & Azure DevOps.
Azure AD External Identities pricing is based on Monthly Active Users (MAU). Based on the AD license type, the first 50,000 MAU is free, post that the charges will vary. For more details please visit the below URL.
https://azure.microsoft.com/en-us/pricing/details/active-directory/external-identities/
For DevOps, you can add external users. You can add an unlimited number of users with Stakeholder access. In public projects, both Stakeholder and Basic access levels grant full access to Code, Work, and Build and Release. But, Stakeholders only get partial access to Tests and Dashboards (no license required). For more information, please visit the below URL.
https://learn.microsoft.com/en-us/azure/devops/organizations/public/default-roles-access-public?view=azure-devops
I hope this helps.
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