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On review, the place where Boruto and ashin Koji are handing out when they realize that the Shinju have attacked Konoha appears to be either one of Orochimaru's hide outs or perhaps Ryuchi Cave.

...In the Boruto Anime, a mini-arc where Mitsuki went awol for a bit involved Boruto and several others going to Ryuchi Cave to find a lead and, due to a misunderstanding, Boruto was made to take the trials to become the Snake Sage. The misunderstanding was cleared up but given that all the "filler" in the Anime is broad strokes canon I'm wondering... It's not like they can go to the Toads to learn sage techniques, but Ryuchi Cave is partially in another dimension so might have been untouched by Omnipotence.