Sanji conqueror haki is probably dormant. Zeff said it in Baratie arc, with his own turn of phrase. Or at least it is what I think.
There is no way Sanji does not deserve conqueror's haki. Of course, Oda might not give it to him, but Sanji has every right to be a conqueror. The ones who say Sanji does not have "Kingly ambitions" because he does not have a dream related to power are wrong, and they know it too. It's just hating the character at this point, they know Katakuri have it. They know Whitebeard have it. They know Chinjao have it.
In conclusion, Sanji have all the rights to have it. But only Oda can confirm this.
Yeah, this is what I meant.
I also agree about "deserve or not" topic, Oda didn't even gave detailed explanation for everything Haki, so it can be changed to fit what Oda wants (just like ACoC basically CoA 2.0). I also think this topic is tainted by the fans' dislike towards Sanji.
But anyway, if we view pessimistically, as in looking from people who doesn't want Sanji to have CoC, everything boils down to not wanting Sanji to be strong/stronger than he is.
And what I talked about earlier is related to this. Be like Kidd for example. He has CoC but didn't utilize it.
So, coupled with Sanji already have Ifrit (so he doesn't need ACoC), I think the middle ground solution is giving him CoC without Sanji ever utilizing it (thus not affecting his powerlevel). It can make both lovers & haters accept it.
P.S : I personally think Sanji already have a lot of stuff for his character, normally I don't give a damn he has CoC or not. My only agenda of Sanji having it is just so that Yamato can join 🤣