Small and resource-constrained organizations increasingly adopt public cloud platforms such as Microsoft Azure and Amazon Web Services (AWS) to gain scalability and reduce infrastructure costs. However, these organizations face persistent security challenges due to limited budgets, skills shortages, and immature governance structures. Misconfigurations in cloud environments are now among the leading causes of data breaches, yet many small teams lack the expertise and tools to manage these risks effectively. Cloud Security Posture Management (CSPM) has emerged as a key approach to address this gap by continuously monitoring configurations, enforcing compliance, and automating remediation. This review examines how CSPM is implemented in Azure, AWS, and hybrid or multi-cloud environments, focusing on its applicability to resource-constrained organizations. It analyzes native CSPM capabilities such as Microsoft Defender for Cloud, Azure Policy, AWS Security Hub, and AWS Config, and compares their coverage, automation, compliance support, and cost models. Findings indicate that while Azure and AWS offer robust posture management features, their complexity, consumption-based pricing, and skills requirements limit adoption in smaller organizations. Hybrid CSPM platforms provide unified visibility and standardized compliance but introduce additional cost and integration challenges. The paper concludes with practical recommendations and a tiered roadmap for SMEs: start with built-in CSPM tools, enforce critical policies, and gradually integrate automation and compliance frameworks. Future research should focus on lightweight CSPM patterns and usability studies to ensure these solutions close, rather than widen, the security gap for small organizations.