He literally said he got the techniques from documents and ruins. Stone tablets are known as ruins, even the stone tablet in the Uchiha naka shrine is called a ruin.
But if you don't believe naruto can use it until he shows it, what about Sasuke?
Sakura doesn't have a blood line limit bro, she's just basic so it just makes Sarada and ordinary Uchiha like Indra's son or any other Uchiha.
I don't know why she's wearing glasses though, even Obito was wearing goggles and putting eye drops in until he awakened his two tomoe sharingan.
Sasuke marrying a senju/uzamaki will lead to a collaboration of Uchiha and senju powers creating a baby born with six path powers. Not sure about the hyuga though.
You have a point on Haruno having no bloodlimit which would prove that it's not compatible with Sasuke blodlimit for a better deal..
Zetsu need decades to make that bloodline original or get it back to the source because Indra had no choice but to lay with a normal chick pushin his blood away from the source.. (He's already too far away from the source, so his kids an so forth will have to do way more to get back to the source power)
On Obito though I think there's a good explanation for his eye drop problem..
He was a kind kid without too many worries (For a Uchiha, that almost impossible) an always smiling.. Uchiha need conflict an Obito didn't have much of it just losing to Kakashi.. I think his eye drop problem comes from his doujutsu not bein awaken from strees or conflict causing his eye to water.. (It's not really implied that blindness was the cause of the eye drops IDT)
He has one of the best MS tech's once he awakens it too. I think it come from bein dormant for so long.. He was older than ever Uchiha I think before he awaken 1tomoe..
