Korg uses the Pi Compute Module 3 [0] in at least three of their products (wavestate, modwave, opsix), with Korg being one of the major synth manufacturers and overall annual keyboard synthesizer sales in the US alone being over 100K units. Don't have hard evidence but am assuming that Korg has sold more than 10K units of those three products.

[0] - https://www.raspberrypi.com/success-stories/korg-synthesizer...