Another interesting example of this is ZynAddSubFX [1]. Although there is not a company built around this (to the best of my knowledge), they do sell binaries

Another interesting example of this is ZynAddSubFX [1]. Although there is not a company built around this (to the best of my knowledge), they do sell binaries while leaving all of the code open source. [1] https://zynaddsubfx.sourceforge.io/ https://zynaddsubfx.sourceforge.io/