Goku does reach a state of immense power in the manga that rivals that of a God of Destruction. However, the specific title and all its implications might not be straightforwardly assigned to him. It's a complex development within the story.
Vegeta could be a great rival. He might see Goku's new position as God of Destruction as another thing Goku has achieved that he hasn't. This could fuel their competitive nature even more.
Goku becoming a God of Destruction could mean a new look for him. Maybe his Saiyan armor would transform into something more fitting for a god, with a more regal and powerful appearance. His power level would skyrocket, and he could start to have an influence on the balance of the universe. He'd also likely have to deal with other gods, which would lead to some interesting interactions.
One interesting concept could be Goku's transformation into a God of Destruction - like form. It might involve new powers and a different way of handling battles.
One idea could be Goku struggling to adapt to the role of God of Destruction. He's used to being a protector, so having to destroy planets as part of his new duty would create a great internal conflict.
One interesting 'God of Destruction Goku fanfiction' could be where Goku takes on the role of a God of Destruction in a different universe. He might have to deal with new threats and use his Saiyan powers in unique ways. For example, he could face off against an enemy that can manipulate time and space, and Goku has to find a way to overcome this using his God of Destruction powers.
Another option is Tumblr. There are many Dragon Ball Z fans on Tumblr who create and share fanfiction. You can search for relevant tags such as '#God of Destruction Goku fanfiction' to find posts related to this topic. However, the content on Tumblr can be a bit more scattered compared to dedicated fanfiction sites.
Goku's training would likely involve learning about the history and responsibilities of the Gods of Destruction. He'd need to study under other gods or perhaps even be mentored by Whis or Beerus. This would include not only physical training but also mental and spiritual training. He'd have to learn to balance his newfound destructive power with his natural Saiyan urge to fight and protect. So, his training would be a complex mix of different elements.
In some Naruto fanfictions, the concept of Naruto killing a God of Destruction might seem far - fetched. However, it could be possible in a fan - created alternate universe. Writers might give Naruto new powers or abilities that allow him to take on such a powerful being. Maybe he acquires some sort of ultimate jutsu or taps into a hidden power source within himself.