Any thread that has a public share link can be shared publicly. Anyone who has access to the link will be able to view the thread and discussion, and sign in or sign up, to join it.
If you're just getting started on Threads, sharing a thread publicly can be a great way to get your team involved in Threads.
Note: only organization administrators can enable or allow public share links. This can be done under the Security Settings in the organization settings.
Here are a few ways to use public share links to show your teammates how to use Threads:
Start a weekly check-in thread: If you have a weekly check-in meeting with your team, try doing it asynchronously over Threads. Start a thread with context, and what you want updates you want your teammates to comment on the thread with. Copy the public share link, and send it to your team.
Move a conversation from Slack: Discussions in Slack can get overwhelming quickly, and it can be hard to track down the conversation later. Copy and paste the discussion, and put it in a thread. Copy the public share link, and send it to your team on Slack and ask them to continue the conversation there. The discussion will be naturally structured, and everyone will be able to refer back to it afterwards.
Share ideas or feedback: Start a thread around a topic you want to discuss. Copy the public share link, and send it to the people you want to discuss with. Your teammates will be able to view the thread, and participate as well. Your discussion will be easy to follow, you won't lose track of it, and it's easy for others to join as well.