Anyone well known who wants to speak out about what's been happening on reddit? Louis Rossmann? Apollo dev? John Oliver (one can dream)... or maybe former Reddit mods who were kicked out?
Anyone who has a story and who understands they'd have a massive impact by giving an exclusive AMA on a Lemmy or Kbin instance.
This could be announced a few days in advance to make sure all remote instances follow the AMA community.
Word of mouth marketing is the best strategy right now. Look how lemmy user base spiked in recent days. More people will look for alternatives after 3rd party apps stops working on July 1st. In the meantime, spread the word on reddit.