Full-stack agile refers to implementing agile practices across an entire organization from top to bottom. The New Zealand Debt Management Office is implementing agile to better respond to changes and deliver business value sooner. They are using scaled agile framework (SAFE) principles but customizing it to their needs as a small team by having a single release train and integrated DevOps. Regular feedback loops, funding approvals in iterations, and focusing on delivering business value are part of their agile transformation.