Who wants to join?
This whole post comes from my experience joining and trying to use Peertube.
The immediately obvious problem is getting creators to post on Peertube which is an entirely separate issue.
Even once I did decide I wanted to join Peertube and try to find all the content I could, I still ran into issues and it just wasn't a smooth experience at all. I'm fine with that as I understand the fediverse works differently and Peertube is a relatively small project (especially compared to YouTube) and I can accept that because I support what Peertube is doing as an open source federated platform. However, most people don't care about all that and even if they hear about Peertube and creators start moving there, regular people will still struggle to use it in its current state.
"Default" instance
Creating an account is confusing and the whole "choose your instance" is extremely unintuitive for new fediverse users. Obviously this isn't unique to Peertube, but other fediverse platforms like Lemmy and mastodon have solved this by having a "default" general instance to direct people to (e.g. lemmy.world & mastodon.social).
Search/Discovery
This somewhat goes hand-in-hand with the previous point, but it's really hard to search and find new creators/videos. Part of the reason is searching in most instances will on search that instance and maybe a few other instances that are specifically federated with yours.
The closest to a "universal" instance I've found is peertube.wtf, but it is extremely slow for me and sometimes just doesn't load at all. Maybe this has to do with the fact that it is also searching so many federated instances, or maybe it's because it's based in Denmark and I'm in the US. Either way, I created an account but it was basically unusable so I switched to TILvids which seems to have a decent amount of creators but isn't federated with many other instances.
There's also Sepia Search but it honestly doesn't seem to perform great and it's very unintuitive to have to go to a different website to search, then the finding a creator/video but it goes to that instance, so to subscribe, comment, like, etc. you need to find a way to open that video within your instance.
As far as I know there's nothing that works in the US