This sound has mystified me for years. On the surface it sounds like it’s not much more than a simple sine lead. But it also has a gorgeous soft grit to it as well. If anyone has any idea what kind of techniques or effects might be behind it, I would love to know.
Sounds to me like a pluck with a sine wave, some fm and possibly bit crush distortion (in serum this is called downsample.) when using fm, make sure the second sin wave (the one applying fm to the first) is an octave or maybe even 2 up, and that its volume is turned all the way down so that it isn’t making noise on its own.