For video hosting? Good luck, that's almost certainly never going to happen. There is not one single competitor to Youtube even from corporations, there is no way any decentralised solution will work long term, especially not if you are expecting features like 4k or 60fps+ content.
Not quite - NewPipe is a YouTube client as well. It's just that it also support PeerTube (a decentralised video hosting solution).
For YouTube, NewPipe is an anonymous account-free, ad-blocking client. You can import your current YouTube subscriptions using a Google Takeout dump (the NewPipe app gives you instructions) and you can add more channel subs directly in the app.
The benefits are no YouTube ads, and it's privacy-friendly but with channel subs - you're escaping the algorithm. To get the benefit of subs on YouTube directly, you need to login, which means they're mining your video watching data and using it to target you (and possibly sell that data to others).
Not quite. From LibreTube's GitHub page on their differences:
With NewPipe, the extraction is done locally on your phone, and all the requests sent towards YouTube/Google are done directly from the network you're connected to, which doesn't use a middleman server in between. Therefore, Google can still access information such as the user's IP address. Aside from that, subscriptions can only be stored locally.
LibreTube takes this one step further and proxies all requests via Piped (which uses the NewPipeExtractor). This prevents Google servers from accessing your IP address or any other personal data.