Wave/Particle duality of quantum objects (quanta) is a bit like bicycle/car duality when looking at motorcycles. Light isn't a wave or a particle, but it has properties of both. Motorcycles aren't pedal-powered bikes or cars, but have properties of both.
Right - that's what I'm saying. But this article seems to think that if you make a bicycle out of cars then you have a motorcycle.. Unless I'm not understanding it.
AFAIK gravity waves are ripples in actual space (mechanical waves) - not a property of "gravitons".
When it comes to duality it’s the particles that exhibit wave-like properties individually.
And waves exhibit particle behavior because waves are particles and particles are waves. Light comes in waves. But when we see light it doesn't mean we are seeing a single light photon.