Melbourne Instruments is an Australian company that builds high end hybrid synthesisers with analog and digital oscillators paired with analog filters. They also have some really unique motorised knobs that turn by themselves as you change presets.
Check them out at https://www.melbourneinstruments.com/
And they are using Elk Audio OS for the FX, digital filters and wavetable oscillators, and knob motor control. They have also been generous enough to share the source code of their instruments. If you’re curious, take a look at: Melbourne-Instruments · GitHub