This answer comes from the Interconnected community forum. 👌
I want to open the Messenger when a certain button on my site is clicked, how do I set this up?
Eric says "If you want the Messenger to open when a button on your site is clicked, you can build what’s called a 'custom launcher'. This guide will show you how to create a custom launcher."
Read more from other community members for tips on doing this in a Shopify store.