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
The question is more “how many people on Lemmy know about the ml political stance”
Posts like this (https://feddit.org/post/3912054) with 205 comments show that most of the people are usually aware.
For new joiners, there is a post on !newtolemmy@lemmy.ca about this.