I'm neither an experienced Hatha Yoga teacher nor an especially diligent Hatha Yoga student.
However, I've found that combining harmonica playing with certain asanas can be helpful to both beginning and more advanced Hatha Yoga students.
All levels are helped in maintaining breathing focus (pranayama) and flow (vinyasa) during and in between asanas.
And some of my students who are advanced practitioners have said something like this (said by one man after working on the Eagle Asana, garuda asana while playing his HarMantra™):
"This is the fastest I've ever been able to get into the pose, and the longest I've been able to maintain it..."
All of the asana that I ask my students to do during a HarmonicaYoga™ workshop can be done, at their simplest levels, by total beginners.
Of course, the more advanced Hatha Yoga students will do more advanced versions.