I just insert the Tragedy of systemd video as my usual response to these threads.

You can do that via the AUR, it’s called cosmic-epoch-git if you have enough ram and time to build it

I didn’t even know Lemmy existed until last week (when I specifically searched for a Reddit alternative) even though I heard about Mastodon.

And it might be confusing to decide where you need to register and what’s the difference without reading up how the Fediverse works. Most people don’t care about that.

Also if they are based on the same technology why I can’t use a Mastodon account to login/interact with Lemmy (conveniently)

I guess if we ever have Nomadic identities most of the above could be solved? Except that Lemmy is still almost completely unknown for most of the people.