Unlike CS:GO 2D overlay sprites, CS2 smokes are genuine volumetric 3D fluid simulations mapped into a local voxel grid.
Inside C_SmokeGrenadeProjectile:
m_bDidSmokeEffect(bool)m_nSmokeEffectTickBegin(int)m_vSmokeColor(Vector3)
Setting the active smoke entity's duration tick offset or zeroing out the particle rendering component removes the volumetric cloud while keeping standard grenade collision intact.