There is plenty of proof. Six Paths chakra can be acquired from Hagoromo, by combining the chakra of Hagoromo's sons — Indra and Asura — to form the Rinnegan, or by becoming the jinchūriki of the Ten-Tails. Naruto and Sasuke received their six paths yang and yin power directly from Hagoromo. Naruto had the chakra of the tailed beasts within him that they gave him, not the actual tailed beasts. That chakra had absolutely nothing to do with being able to use RSM.
No one is talking about the Six Paths Chakra, so I'm not sure how his sons or the Rinnegan have any relevance. We're talking about the Six Paths Senjutsu, which is different from Six Paths Chakra. There are ways to acquire the Six Paths Senjutsu:
-Being Kaguya's close relative - Hagoromo and Hamura naturally had the Six Paths Senjutsu by inheriting it from their mother.
-Becoming Jubi's Jinchuriki - Madara and Obito.
-Possessing the Chakra of 9 Biju - Naruto.
-Possessing the Tenseigan - Toneri.
Naruto acquired the Six Paths Senjutsu because Obito gave him the Chakra of all 9 Biju's, then Hagoromo physically manifested them inside Naruto and that gave him the said power. It had nothing to do with Seal.
Six Paths Sage Mode (六道仙人モード, Rikudō Sennin Mōdo) is a form which empowers the user's abilities to a far greater extent by utilising the Six Paths Sage Chakra. It is a divine state gifted by Hagoromo Ōtsutsuki to those who have an iron faith and the guts to never give up. -4th databook
Hagoromo's gif to Naruto was that he made the Biju's physically manifest inside Naruto, which enabled him to use their Chakra and powers. That is what the databook meant. Naruto had their Chakra's prior, but couldn't use its power until Hagoromo gave him the gift.
Proof in manga: Hagoromo says he is giving the power to Sasuke, and this proves he gave it to them both.
Hagormo gave Sasuke the Rinnegan as it was stated in the databook. No one denied that apart from Sasuke's wankers who think he awoke it. Hagoromo's gift to Naruto is he made the Biju's physically manifest inside Naruto and that enabled him with RSM.
That should be plenty of evidence for you. It's canon that he received the power from Hagoromo. Clear as day.
You didn't provide me evidence. It's just your incorrect interpretation of the databook. Hagoromo's gift to Naruto and Sasuke were this:
Permanent power: Rinnegan that he gave to Sasuke and manifested the Biju's inside Naruto, then Naruto later combined their Chakra for RSM.
Temporary power: The Yin and Yang seals that contained half of Hagoromo's Chakra each. Yin Seal allowed Sasuke to extract Senjutsu from the seal, and Yang Seal allowed Naruto to heal people. The seals returned to Hagoromo after his moon Chibaku Tensei, meaning Sasuke can no longer use Senjutsu and Naruto can't heal people anymore.