Background. Within the software industry, it is commonly estimated that software professionals invest a substantial portion of their work hours in the process of understanding existing systems. In this context, an ineffective technical onboarding process, which introduces newcomers to software under development, can result in a prolonged period for them to absorb the necessary knowledge required to become productive in their roles. Goal. The present study aims to explore the familiarity of managers, leaders, and developers with software visualization tools and how these tools are employed to facilitate the technical onboarding of new team members. Method. To address the research problem, we built upon the insights gained through the literature and embraced a sequential exploratory approach. This approach incorporated quantitative and qualitative analyses of data collected from practitioners using questionnaires and semi-structured interviews. Findings. Our findings demonstrate a gap between the concept of software visualization and the practical use of onboarding tools and techniques. Overall, practitioners do not systematically incorporate software visualization tools into their technical onboarding processes due to a lack of conceptual understanding and awareness of their potential benefits. Conclusion. The software industry could benefit from standardized and evolving onboarding models, improved by incorporating software visualization techniques and tools to support program comprehension of newcomers in the software projects.