Context: Open Source Software (OSS) is a vital public good, included across most of modern software stacks, significantly impacting GDP and national tech growth, while supporting interoperability, sovereignty, and transparency. However, systematic measurement of governmental OSS adoption remain limited. Research Aim: This study contributes to digital government maturity indexes by analyzing policies and support actions leveraging OSS for software reuse and collaborative development across 16 digitally mature countries, and proposing potential indicators for said indexes. It examines OSS policy formation, stated goals, key actors, and support mechanisms. Methodology: A qualitative approach is used combining desk research of policy documents with semi-structured interviews of government representatives, producing detailed country reports. These are cross-analyzed, focusing on OSS policy promotion, rationale, and implementation support. Results: Policies facilitating OSS reuse are widespread, targeting both inbound acquisition and outbound sharing, and are predominantly governed by central public sector organizations. Policy goals include interoperability, digital sovereignty, transparency, and cost efficiency, with security framed both as a risk and strength. Implementation is supported by diverse Open Source Program Offices (OSPOs) at multiple government levels, which foster capacity building, resource pooling, and sustainable project governance. Indicators are synthesized and proposed across 14 areas covering policy incentives and design, and implementation and support. Conclusions: OSS is a strategic enabler for public sector digital transformation. Clear policy frameworks, coupled with institutional support such as OSPOs, are essential. International digital maturity frameworks should expand OSS indicators to better guide and assess government adoption and impact.

翻译：背景：开源软件（OSS）作为重要公共品，已嵌入大部分现代软件栈，对国内生产总值与国家技术增长产生显著影响，同时支撑互操作性、主权性与透明度。然而，政府层面采用开源软件的系统性衡量仍十分有限。研究目标：本研究通过分析16个数字化成熟国家的开源软件复用策略及协作开发支持政策，提出适用于数字政府成熟度指数的潜在指标，以推动该领域评估体系完善。研究内容涵盖开源软件政策制定、目标声明、关键行动者及支持机制。方法：采用定性研究方法，结合政策文件案头研究与政府代表半结构化访谈，形成国别详细报告。通过交叉分析聚焦开源软件政策推广、实施依据及执行支持。结果：促进开源软件复用的政策已广泛存在，覆盖内外部双向共享，主要由中央公共部门主导实施。政策目标涵盖可互操作性、数字主权、透明度及成本效益，其中安全性被同时视为风险与优势。各级政府部门设立多样化开源项目办公室（OSPO）支持政策落地，促进能力建设、资源整合及可持续项目治理。最终在政策激励与设计、实施与支持维度提出14类综合指标。结论：开源软件是公共部门数字化转型的战略赋能要素，需通过明确政策框架与制度支持（如OSPO）共同推动。国际数字成熟度评估体系应扩展开源指标维度，以更有效引导与衡量政府应用成效。