However, I am critical of you on one minor point. I would argue that the Preta Path jutsu that Nagato has developed is not necessarily a technique of his own, but rather it is a more evolved version of the Rinnegan's original technique, showcasing that Nagato was the most skilled or pure Rinnegan user.
Perhaps Sasuke and Madara have not reached the same level as Nagato, so they can only utilize the weaker form of the Rinnegan's absorption, but when they do, I imagine they would also gain the ability to utilize the bottomless sphere, or "Preta Path" jutsu.
The evidence to support my claim is when Obito mentions using the Human Path ability on Yamato:
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It seems likely that a "Path" ability is not restricted to only Nagato and they are not different jutsu altogether, but they are in reality one and the same, where one version of the same technique is simply more refined. However, I grant that Nagato had developed his Rinnegan further than the others, which is what allows him to utilize the more powerful versions of the Rinnegan's inherent techniques.
Additionally, it is possible that the "upgraded" versions of the Rinnegan's original techniques are indeed Nagato's own, and that would mean that any Rinnegan user would develop his or her own unique Rinnegan techniques based off the originals. However, based on the page I posted, I am not sure how plausible that hypothesis is.
Yes, Preta Path is an amplified version of the existing Rinnegan absorption ability. It's shown to have clear difference in how they work. Rinnegan dogs don't split from Animal Path but they split because Nagato uses Amplification Summoning Technique to make them split.
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To say Paths aren't restricted to Nagato only makes no sense. Kishimoto had emphasised throughout the manga and databook as Six Paths of Pain or Pain's Jutsu are accessible to Nagato only. Databook 4 goes up to Naruto The Last and Nagato is the sole user of his Path techniques, not any other Rinnegan users are mentioned. Obito's statement was just a bluff.
