If, despite your best efforts, friends wind up going to Bluesky or Threads instead of the Fediverse, encourage them to enable federation so you can still interact with them from here.
Bluesky: Instructions here: https://fed.brid.gy/docs#bluesky-get-started (TL;DR: follow @ap.brid.gy on Bluesky).
Threads: Turn on "Fediverse sharing" in your account.