generally , what do you use ?

https://joinpeertube.org/

is the app good and lightweight ? my phone only has 1GB of ram and and a CPU with erectile dysfunction

Uh sorry, is there a good way to tell RAM usage on a different phone with more RAM? I didn't find any usage number in the settings. It's a ~50MB app. So at leat they didn't include as much bloat as other apps do... You can try it. It allows you do watch videos right away, without signing up.

I don't understand the question; the Fediverse has nothing to do with apps. Apps are just frontends that access services.
But you asked for a YouTube alternative, and for that, your phone's hardware is completely irrelevant.

Or are you planning on installing a PeerTube instance on your phone?

They might be talking about the Peertube app.

I think they want to know if there is a PeerTube client (ideally an "official" one) that runs on such a weak phone.

yes I understand , I asked about the app after I asked about the replacement basically I want the that front end to access a YT replacement
no , I'm not planning to run a PeerTube instance on my phone

You only need a Peertube account – and the app, if required – if you’re a content creator and want to upload your own videos. You can watch videos without needing any account at all, either in your browser or on your mobile using an app, such as the Peertube app or NewPipe. SepiaSearch offers a comprehensive video search (covering a large number of selected instances).

If you want to subscribe to channels, watch, share or comment on videos in the Fediverse, you can do so from your Fediverse account, i.e. from Friendica, Mastodon, Sharkey, etc. You can also subscribe to Peertube channels and watch videos using your Lemmy account. I’m not sure, though, if all the features are available with Lemmy.

Sadly I think not , Android is quite an awful OS almost in every regard to performance
I think the only way to see RAM Usage is threw the Developer tools and logging

Check out NewPipe. or PipePipe for automatic ad skipping. Does YouTube and PeerTube. "Share" video links from a PeerTube site with it to open it in the app.

The Official App requires about 170MB RAM while watching a Video. Not sure about CPU usage but it seems light enough. NewPipe, the YouTube client, also allows you to browse PeerTube and is very light in my experience (RAM usage is about the same though)

AFAIK, Peertube is your only option.

There's this platform called Means TV.
https://means.tv/

Peertube or Odysee

Odysee being more active than Peertube

Odysee is not federated. Its decentralisation is based on LBRY blockchain.

I’m not sure, though, if all the features are available with Lemmy.

They are on PieFed.

I tried to subscribe to a PeerTube channel on Lemmy, but it looks that it stuck on "Subscribe pending". However, copy-paste of a video URL works, and I was able to watch and comment the vid using Lemmy.

Depending on the service, you don't even need an app. The instances' sites can usually run fine on browsers, and when they don't, Lemmy, Mastodon and the sort can usually play the videos embedded.

Odysee has native RSS so setting up fediverse bots should help at least have some form of integrated feed.

Video softwares are a tad scarce, the main ones being Peertube (based on Youtube) and Loops (based on TikTok).

Peertube channels appear as communities on Lemmy from my experience. Loops I don't think I've seen being federated to Lemmy before, so I imagine posts from instances using it get treated as pure microblogging, meaning barely anything gets fetched by Lemmy.

Odysee has a lotta nice to haves, like filehosting, but I'll be damned if most comments sections I see aren't full of the craziest of people.

that's actually the best answer I got here , thank you

Just like YouTube

...right, sorry. I just figured that out. there's some serious bad omen on me at this platform i keep embarrassing myself. i need to be more careful

really? i didnt see any of such comments- probably i got lucky...

Don't worry, this series of tubes is indeed complex