Wait, does this whole shutdown include the chat on the main site?
They only discontinued first-party applications off-site. That is, the standalone Facebook Messenger for Windows program and Facebook Messenger for Firefox add-on. They are trying to push people to use the site, which I honestly can't because I seem to always find new and creative ways to crash my loving browser, and in general it is a hassle to use the browser for
live chatting nowadays.
It's not AFAIK
Hmm, I wish I could check debugging on this and see what is being pinged back to me.
Edit: Oh by the way, "is typing" messages are supported. I know that's somewhat standard now, but I was hoping if they even bother, maybe other notifications are relayed.