Oda going to retcon that Sanjis had FS since post timeskip.
Current Oda would say it's Feet Sniffing haki especially given how Sanji acted on Sabaody. Oda and his horny gags man.
FS Sanji would make too much sense, along with Usopp and ideally Nami imo but then again its meant to be extremely rare, even more so than CoC supposedly going by story portrayal But I'd still fit Sanji and especially Usopp well though, bah.
I expect Yassopp will have it though or Beckmann at least.
But that might make it "too common" and too awkward to write in fights, idk. It'd already caused issues before but I do like you need completely stoic focus and thus emotional clarity to use it or w/e. No emotional instability or disruption.
What is it with top-tiers and losing or nigh-losing to one unguarded attack though. Oden, Kid, Garp, and now Gabanβ¦.
Lazy writing.