It uses activity pub, a protocol that allows servers to share content. So when you post on an instance, it became available for other instances to consume your content.
About slowness, it can be that your instance it being rate limited, or it is not powerful enough to process all its users. You can try another instance.
I host it in a Truenas BSD Jail, and the process was as straightforward as compiling and running any other Rust / Postgres project. Which error did you get?
Another option is SearXNG. It's meta search engine, which means that it aggregates other search engines like Google and Bing but without tracking or logging, because your searches are proxied using a public instance, that will mix your search with the ones from other people.
And about default search engine, don't know what you're talking about, both chrome and Firefox allows this, in mobile and desktop.
If you remove the app-platform role from Nextcloud by separately hosting the individual apps, what benefit do you get from having both Nextcloud and File Browser?
Nothing really. For almost any Nextcloud feature out there, you can find a server app that does the same.
But that's the point in my opinion. I don't want to waste time managing tons of apps if I can manage one Nextcloud instance. Nextcloud basically decides for me what's the best way to get those features running, so I don't need to figure out myself.
Now if you're into self hosting one container for each feature, go for it, no reason to not do so.
Anyone that has video drivers and flatpak should work in your case. If you dislike Ubuntu and don't like the direction, usually poops and mint are the ones recommended.
It's a reverse proxy server that you install in both your server and a VM in the cloud, and it tunnels your server over the VM, like Cloudfare solution.
Why don't you install flatpak on Ubuntu, make the packaging migration before doing the OS migration so you can evaluate your workflow with the new packaging system? Afer you're used and confident with flatpak, backup and restore the flatpak folder into fedora and you transition should be smoother (don't need to worry with 2 stuff at the same time)
I like Thunder