Another pro tip: if you want to use Messenger in Chrome it sends you to the Play Store, but you can avoid that redirect when requesting the desktop version of the page. It's a bit clunkier Messenger but it totally works.
My primary use of Facebook is as a chatroom for clubs/boards at this rate. kb had suggested Metal for those who actually use Fb, but for anyone who uses it mostly for chat then third party apps are muchanging nicer and less of a battery drain. I read there were a few preferred ones, and Disa.im works suitably for my needs.
Disa apparently works with multiple platforms which I also can't find a definitive list online either for.... Checking the app on my phone right now says Facebook, text, WhatsApp, and 'Third Party Plugins' that you have to search for. This article is what I used to find the app, if you're interested. It has 3 other alternatives to Fb chat.
Holy nuts. Didn't even know it was that old until y'all brought it up. I would have used it a while ago if I knew about it. I'd assume it's more polished in this iteration. That said, Disa can be a bit janky at times with simple things like not opening the app when I click the notification and ordering the messages in reverse chronology (that's just my own peeve, not a bug... just a feature!). But, on the whole, it serves its purpose for me reliably, and I'm happy with that alone.