In collaboration with the project Klasse Klima, the second issue of Branch Magazine explored how a self-hosted Matrix server running on a Raspberry Pi can serve as a secure, climate-conscious infrastructure for collaborative learning and activism. Building upon the medienhaus/-stack, a customizable and energy-efficient communication platform was developed—enabling digital sovereignty on a collective level: federated, privacy-compliant, and locally controlled. The initiative combines technical resilience with ecological responsibility and a community-based approach to education.