During Wano arc we’re given a demonstration of Advanced Armament Haki. Luffy uses a blast of haki to blow apart a tree without even touching it.
That’s impressive, and it’s something we’ve seen before.
Even if Rokuogan is a shockwave, it should never be able to damage Luffy like so. He’s rubber, inside and out. Yet, it does, and brutally so. Note, the CP9 arc comes after the Sky Island arc where the basics of Observation/what would become Observation were established. It is probable that Lucci was able to incorporate some aspects of Haki into his fighting styles, which is why he was so far ahead.
Oh, and Lucci’s Pre Timeskip Vivre card shows him as having Haki.
Ah, but the counter is simple. All the other CP9 members show them having haki, where they clearly did not. The counter to that? Every other card is a post timeskip card. You can check their ages, Lucci has his own post timeskip card which came out earlier.
As you can see, his current card is updated with his new age and position.
There are many cards which have both pre and post timeskip counterparts, but the pre-timeskip counterparts of say — the Straw Hats — don’t gain the Haki of their present/current selves. So we have evidence of Lucci using a Haki like move, and Lucci being marked as a Haki user on his card…
*Theory by GabrielMichaelson