Digital technologies have become increasingly relevant to music education, offering possibilities to enrich pedagogy through feedback, visualization, and accessibility. Yet, many existing tools remain teacher-centered or designed mainly for performance settings, thereby limiting autonomy and skill-specific training. To address this gap, we developed a modular, open-source mobile application designed to support the learning of trumpet fingering technique through structured exercises. The app guides users through a three-step cycle (rest-listen-play), enhanced with authentic audio samples, visual traffic-light cues, and fingering diagrams, aimed at supporting the development of sensorimotor skills and independent practice routines. This paper presentation reports on an exploratory study that investigated the perceived usefulness and usability of the application with twenty adult trumpet learners. Data were collected through anonymous in-app usage logs, questionnaires, and focus groups to investigate how learners engaged with the tool in their practice. Participants highlighted that the app 1) encouraged consistent and focused practice, 2) helped overcome challenges of limited teacher availability, and 3) offered motivational advantages over traditional paper-based resources. They valued features such as the intuitive design, the integration of professional sound references, and the option to rely on fingering images other than traditional staff notation. These preferences underscored the importance of offering alternative notations and flexible interaction modes to accommodate diverse learning needs. At the same time, participants suggested clear improvements: more exercise variety, gamification to sustain motivation, and stronger feedback mechanisms. They also imagined the tool being used for other instruments and contexts, not only the trumpet. The authors built on these reflections and explained that the flexible modularity of framework makes such extensions possible. These considerations illustrate how aligning technological solutions with pedagogical principles can transform digital tools into inclusive and engaging companions for music learning. The study demonstrates that open-source frameworks not only facilitate innovation but also enable collaborative refinement of music education technologies across communities. Beyond trumpet pedagogy, these insights inform the design of adaptable tools that can empower independent learners, complement classroom teaching, and support inclusivity in diverse cultural and educational settings. By foregrounding user perspectives, this research contributes to the broader discourse on how music technology can expand equitable access and meaningful engagement in music education.