Of course that he regretted that he couldn't save her bc he loves her but do you really meant to tell me that Obito who loved Rin so much and wanted to confess to her so many times but in the end wasn't able to has no regrets about that ? That seem so cold to me Sorry but that makes no sense to me any person would have regrets about this kind of matter .
I believe this whole "Obito regrets not confession" is an assumption.
What Minato did is kind of an confession and you do realize that it shown like that and only that bc MK is created after NS only with very much less development bc NS is the main paring
That wanst a "kind of confession" he just complimented her, Naruto almost did that if he didnt told her that she was still the same when she asked him if she was more feminine.
Not really the impact isn't lost at all Sakura also feels unworthy of Naruto's love for her this is were his confession comes imo.
How this will changer her "unworthyness", i think her being unworthy of Naruto's love on that specific scene had nothing to do with whatever feelings she might had for him, she felt like that because she felt guilty of putting her desires into Naruto it in way felt like she was using him and was being a burden to Naruto hurting him because of his innability of fullfilling a selfish promise she unintentionally forced into him.
On whose promise no longer holds since it was broken by her.
Naruto believed that until Sakura's confession in LOI since then its a different playground .
I dont know, if any he was really shocked that she loved him so much that she was going to kill him to save Sasuke and even if it means letting Naruto hater her forever to relief the burden of the promise, that's from Sai's perspective that was forced into Naruto.
There's no conclusion about Naruto's feelings into that part saying it changed is an assumption and there are hints of the opposite since he was jealous at Sakura at some point.
Right now Sakura needs to convince Naruto that she loves him through her actions if Naruto is to believe her and if NS is about to go canon otherwise its LOI again . And still I don't see any sense of that bc NS is foreshadowed to go canon what you said with your example is that Naruto confess but Sakura rejects him sorry don't see that happening at all .
The problem is that it's impossible to prove she loves Naruto thoughout her actions in the moment, because all of them are connected to non-pairing feelings.
THe only way to prove it would be choosing Naruto over Sasuke on equal grounds and i think this scenario is impossible.