Feature Request: Federated groups + native federation support for Group Folders (Team Folders)

Summary

Group Folders (Team Folders) are widely used to manage structured, permission-based data for teams and departments.
Currently, Federated Cloud Sharing in Nextcloud only supports standard folders and user-level shares. This limits cross-instance collaboration when data is managed at the team level.

I propose two related improvements: one incremental and one long-term.

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Option 1 — Incremental (recommended first step)

Allow adding federated users or federated groups directly to a Group Folder, for example:
hr@https://othernextcloudserver.com

Administrators should then be able to assign Advanced Permissions to these federated principals:

• read
• write
• create
• delete
• share

Expected behavior

• When access is granted, the remote Nextcloud instance receives the content under its standard “Shared” section.
• Permission logic remains controlled by the owning Group Folder, including inheritance and advanced permissions.
• No need for intermediary users or manual per-subfolder federation.

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Option 2 — Native Federated Group Folder (long-term)

Introduce native federation support at the Group Folder level.

Concept:

• A Group Folder can be federated as a whole.
• The Group Folder itself becomes a first-class federated resource.
• Ownership, advanced permission inheritance, and centralized administration are preserved.

This could be exposed as a “Federated Group Folder” capability.

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Why this matters

Current workarounds (federating subfolders, using intermediary users, or WebDAV-based external storage):

• Break permission inheritance
• Complicate auditing and ownership
• Increase administrative overhead
• Are unintuitive for administrators and end users

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Use cases

• Cross-company project collaboration
• Holding companies with multiple Nextcloud instances
• Managed service providers serving separate customer instances
• Enterprise environments

The issue names no files, tests, or entry points. Start by reviewing the existing Group Folder permission model and federated sharing behavior described here, then scope whether incremental federated principals or native federation is feasible. Done would require an agreed design and implementation plan before coding can begin.