I love the concept but (at least on mobile Safari) most of it feels unusable.

Same on Brave on Android. But I think that's largely orthogonal to the design, which I like a lot.

The knobs are especially difficult to use (on desktop here). The first two knobs only respond to click & vertical drag - moving up rotates clockwise, moving down rotates ccw. Moving left or right does nothing. The second knob's grab handle is just totally wrong, appearing in only about the 4 o'clock to 6 o'lock position.