From my perspective mails are federated. If I want to explain federation as a concept to someone I always use mail as an example because everyone can write to everyone independent of the provider, you can selfhost it easily, you could move from one company to another (if you use your own domain), protocols are all FOSS.

So at least it’s an open and distributed system. What would be missing for it to count as federated?

I’ve always missed a rating/feedback/comment feature in F-Droid. A lemmy-based solution would be pretty cool.

On mobile you could also have a look at NewPipe. It does not have automated downloads but it shows you a simple list of all the videos from your subscriptions without any algorithm-based recommendations. It shows no ads and is fully open source.

Also supports plenty of services other than YouTube.

Sorry, you’re right. It’s been so long that I’ve installed the app and always went via system settings that I’ve incorrectly assumed it was native.

— incorrect statement removed

Can you reach the server’s IP in general from other PCs in your network? Or is the issue restricted to the nextcloud service?