I've never gotten into using Massive or Serum so maybe I'm not so cool but that sounds like the work of an FM synth to me. (not even sure if either of those that you listed have that capability because I am only vaguely familiar with them). Anyone more versed in this type of synthesis, please correct me. But I think I can at least point you in the right direction.
I agree that this/these guy(s) have some pretty dope sounds.
It sounds to me as though they have several patches set up that are creating the foundation of the song. That buzzing, high pitched one is actually a simple patch with some automation but I am not fluent enough in programming FM synths to guide you specifically, I apologize for that.
If you have an FM synth plugin or one that is native to your DAW, the best way to learn is to experiment with some simple patches, (for example one operator modulating another) then build from there to see what kind of stuff you can come up with. It gets crazy fast if you attempt to apply acute settings with this approach to synthesis, and even automating slight modulations can create some really badass sounds once you get used to it.
