I found a super simple way to refer people to Lemmy.

One simple message:

Try out the Reddit alternative called Lemmy https://phtn.app/

It also has a mobile app: https://vger.app/settings/install

This way a user can just click, start seeing content and what Lemmy is about, and if they want to comment etc. they will be asked to create an account with lemm.ee selected as a default.

This should fix most of the onboarding UX issues, and eliminate the decision fatigue of trying to figure out which instance is best.