Board Thread:Theories and Speculation/@comment-4688597-20150529040116/@comment-945885-20150529071432

According to the databook, the Trusthseeker Orbs manifest when a user unlocks the same power as power of the Sage of Six Paths. The two methods clearly outlined for unlocking that power are using the Six Paths Ten Tails Coffin Seal to become Ten Tails' Jinchuriki, or by using Six Paths Sage Mode, which Naruto achieved after receiving the chakra of the nine Biju and the Sage of Six Paths to become a sort of ersatz Ten Tails' Jinchuriki.

Given that becoming Ten Tails' Jinchuriki can awaken this power, it stands to reason that Kaguya would be able to tap into it. After all, Ten Tails was formed when Kaguya merged with the Divine Tree. Her Expansive Truthseeker Orb was formed by using the Divine Tree to absorb the chakra of the shinobi trapped in Infinite Tsukuyomi.

Kaguya gave birth to Hagoromo and Hamura and passed a portion of her chakra on to them, so it shouldn't be a surprise that they had similar abilities. Though Hagoromo was dubbed the Sage of Six Paths, they obviously both used Six Paths Sage Arts, including the Truthseeker Orbs. Given that the key phrase is "the power of the Sage of Six Paths," they should both be able to use them.

Tenseigan Chakra Mode appears to manifest Truthseeker Orbs. Though the novelization only ever refers to them as a "chakra rosary," they definitely look and behave exactly like Truthseeker Orbs. It's also worth noting that it's a Chakra Mode, not just a dojutsu; the Tenseigan allows Toneri to tap into a tremendous well of chakra that's been sealed away and accumulated for a millenia, giving him strength that's a very close match to Naruto's Kurama Chakra Mode (which seemingly retains at least a fraction of his Six Paths Sage Mode power).