see the thing is you cant compare sashisu with itafushikugi one to one because itafushikugi doesn't exactly have a shoko parallel, because no one really left behind in that trio the way shoko was...and that's its own tragedy imo. that shoko was there too but never really a part of it. gojo says he was alone after suguru left. what about shoko? "i was there too wasn't i?" but that shit wouldnt happen with itafushikugi because they function differently as a trio..
anyway saying nobara is a shoko parallel just bc she's a girl is stupid. nobara simply isn't as passive or pessimistic as shoko is. and also, to me, with shoko and satosugu there's always this distance. it's especially obvious after suguru's defection where satoru and shoko both still obviously care for each other, but both of them think the other doesn't care as much as they do. shoko is pissed that satoru felt alone and satoru is pissed that shoko was just fine with the brain transplant plan. but they don't communicate any of this!! so they both think their care isn't fully reciprocated.
whereas with itafushikugi, i can't see any one of them thinking 'oh these two are leaving me behind' or 'they don't love me as much as i love them'. their dynamic is just different. actually, even if one of them thought this it would NOT be nobara lmao. it would either be megumi post-canon when he's dealing with depression or yuji pre-shibuya where he thought he was eventually going to be executed, but even that would manifest more like "they're going to be fine without me around". regardless, i maintain that itafushikugi aren't one for one parallels for sashisu no matter how you pair them up.