Primebeard=Roger=Garp=>Rocks=Harald=Shanks=>Loki.
This is a free power scaling lesson.
Roger and Whitebeard are a duo from the start of the story.
Rocks and Harald are their versions in the final saga, basically Roger & WB v2.0.
All 4 of them are irrelevant background characters that do not get the spotlight in the present/final saga.
All 4 of them are pretty much equals, placed on the same pedestal in the Kaido's top 5.
Harald is included here by default due to being equal to Rocks who is among Kaido's top 5.
Wano and Elbaf are the two most important allied nations of Luffy/Sun God, the strongest countries that arent affiliated with WG.
Their strongest representatives of the past are Harald and Oden. Rocks said that 2 DFs are needed to bring down the WG.
The sons of those strongest representatives of those 2 strongest allied countries, Loki and Momo have those 2 exact fruits.
Loki is all that Harald was but more, due to a legendary DF.
Momo, by the time of WG war, will be all Oden was but more due to a legendary DF.
Due to Harald and Oden=>WB and Roger, those who will be stronger than Harald and Oden are also stronger than Roger and WB.
Bookmark this and watch it happen. I dont know if Shanks will escape this fate or not but he might also be weaker than Loki and Momo.