Developing legal systems are strengthening regulations on digitalization and cross-border data flows, yet transitional countries still face significant legal and institutional challenges in meeting the stringent commitments of modern Free Trade Agreements (FTAs). For example, the EU’s FTAs with Singapore and Vietnam, and ongoing negotiations with other ASEAN countries, reflect its motivation for a region-to-region framework tied to global data-governance standards, centered on the GDPR’s Article 45(3) adequacy requirement. While normatively influential, the GDPR’s strict requirements and severe penalties pose considerable compliance burdens for developing economies. For ASEAN countries such as Vietnam, legal transplantation from the EU may also risk “legal imperialism” if external models are adopted without regard to local institutional capacities and infrastructural constraints. Vietnam’s legal framework, currently grounded in cybersecurity and state control, provides solid roots for data governance. Yet to thrive in the evolving digital ecosystem, these roots must be complemented by new branches of trust, transparency, and interoperability that extend beyond national borders. This article analyzes Vietnam’s legislative progress on cross-border data flows, identifies practical implementation challenges, and considers implications for future digital trade agreements. Drawing on Japan’s trust-based approach, the article proposes a balanced, model-rooted, resilient yet adaptable roadmap for Vietnam to build trust for cross-border data flows in line with domestic capacity and regional cooperation.