I doubt it - like most Apple things, it probably only works with other Apple things. Most things in the world are not Apple.
I don't think that true in the broad messaging space (speaking of martekshare), mostly because apple limits itself to the portion of the market that happens to own apple products. Facebook is, though.
Meh, everyone I know uses Telegram. I haven't used Facebook messages in years because the feature is apparently not on the mobile website and I'm not willing to install an app that requires suspiciously many permissions.
Here’s a lil trick: if you have to, you can access your Facebook messages on mbasic.facebook.com.
(And on to the point, Facebook has also, of course, WhatsApp, which is massive)
In the comparison of the two companies, Apple is crushing Google in any context. In the US, it's the same if you include other players. Worldwide is a different story.