One thing that would partially help would, at least, a global video search at peertube.com. With channel names you have a problem, as they would not be unique, BUT at least, you could return all users in all instances, and hope people check the avatar. That would make the process more transparent to users, as they would go to peertube.com and see everyone they follow.

BUT, there's a huge problem. When you have a big creator on the platform, like PewDiePie for example. Every instance would have someone creating a fake PewDiePie. So, either the original creator would go to another platform, or they would need to use bots to create they users on all possible instances. So... creator will not have any incentive on using Peertube, as there's no 100% way to know who's the original.