jointhefediverse.net seems to be a commonly linked resource for directing people to join the Fediverse.
Curiously, it does not list Lemmy under the list of Reddit alternatives. Their GitHub README explains why.
Previous relevant discussion: https://lemmy.ml/post/78808
how do you block an entire instance?
Searching for the instance and then tapping on the element gives you the menu that provides the option to block on the third party app Mlem.
I use Voyager, but this helped me find it in the filter settings. Thank you!
Posted a tutorial here for the mobile web version