OLD reddit, I don't think new Reddit can do this, you could add multiple communities together with a '+' sign. Example:

https://old.reddit.com/r/PieFed+fediverse/

Is there a way to do this on Piefed? If not, it's an AWESOME tool imo that majority of people don't even remember or knew existed.

As for URL I haven't heard of such thing. But if you would like to often see the same communities together, create a private feed (link is a shot in the dark, you can find it in "Explore"->"My feeds" at the top in web UI

That requires a login though. Reddit forces us to do that because they have to feed us ads. If we'd allowed custom feeds without a login, we'd get more viewers, hopefully, that might turn into someone that wants to participate.

For someone that says "lemmy is dead", we can create a custom feed with + and share it with folks and show, we're here! But also, again, you can view and don't have to worry about creating an account.

If you want the feed to not require a login you can make it public. Or use an existing one. I think there was also an RSS button somewhere on non-mobile view

Excellent suggestion. But someone would have to know that feed. If we tell someone you can just append categories, that's easier imo. :) But that's also an excellent suggestion.

I guess the vast majority of all the nerdy people who appreciate URL manipulation are already here, with the possible exception of those who noped out early due to the tankie politics of the Lemmy devs who haven't kept up to know the PieFed now offers an even stronger alternative.

I will note that you do not need a login to use custom Feeds - e.g. test out https://piefed.social/f/allcomics - though yeah you currently need an account to create one, unless someone wants to write the code to be able to generate them on the fly.