This question is mostly targeting Devil Fruits but could be applied to other things.
For example, when Newgate attacks Sakazuki, does he use Haki?
I don't think that he was even capable of using haki at this point due to his his already very compromised physical condition. I don't think that he needs Haki when he uses his Gura Gura No Mi to harm a logia user. Just like how Luffy didn't need Haki to harm Enel or Crocodile, If a devil fruits powers can interact favorably with a Logia or they have a natural counter, they do not need to use Haki. I do not think that it is even possible for Newgate to imbue his quakes with Haki because quakes are not physical. They're just oscillations of pressure and have no tangible form. The same can be said for Kizaru's light and Fujitora's Laser.
Also, we see the ability of devil fruit users not needing haki if they have a conducive power with Sakazuki and Ace. Sakazuki never mentions his Haki being superior or even using Haki to bypass Ace's intangibility. He simply talks about having devil fruit superiority as the reason why he could harm ace despite ace being intangible.
I think that Whitebeard's shockwaves, since they penetrate through mediums were effective in reaching Sakazuki's physical body past his Logia body hence why he took damge.
I don't think things that have no physical form can be imbued with Haki. For example, it hards to imagine Kid's Electromagnetic Force or Fujitora's Gravity and even Kizaru's light and Whitebeard quakes capable of being imbued with Haki.
Just think of Foxy's Noro Beams. How would Foxy even imbue that with Haki?
For example, when Newgate attacks Sakazuki, does he use Haki?
I don't think that he was even capable of using haki at this point due to his his already very compromised physical condition. I don't think that he needs Haki when he uses his Gura Gura No Mi to harm a logia user. Just like how Luffy didn't need Haki to harm Enel or Crocodile, If a devil fruits powers can interact favorably with a Logia or they have a natural counter, they do not need to use Haki. I do not think that it is even possible for Newgate to imbue his quakes with Haki because quakes are not physical. They're just oscillations of pressure and have no tangible form. The same can be said for Kizaru's light and Fujitora's Laser.
Also, we see the ability of devil fruit users not needing haki if they have a conducive power with Sakazuki and Ace. Sakazuki never mentions his Haki being superior or even using Haki to bypass Ace's intangibility. He simply talks about having devil fruit superiority as the reason why he could harm ace despite ace being intangible.
I think that Whitebeard's shockwaves, since they penetrate through mediums were effective in reaching Sakazuki's physical body past his Logia body hence why he took damge.
I don't think things that have no physical form can be imbued with Haki. For example, it hards to imagine Kid's Electromagnetic Force or Fujitora's Gravity and even Kizaru's light and Whitebeard quakes capable of being imbued with Haki.
Just think of Foxy's Noro Beams. How would Foxy even imbue that with Haki?
