Personally I'm not into the social media app fad...
never was.
pidgin does / did have facebook chat plugin.
I'm not sure if it is still functional.
You'd have to check it out.
Yet again for the older device lines (770 and 8x0 and given enough time the 900 to come) it's about three issues...

1- Not enough consistent users / tinkerers doing program maintenance, troubleshooting etc...

2- ALWAYS with such distant (I don't even call it 3rd party ...rather 5th cousin removed...) applications run by external parties that rely on keeping a population entertained (meaning consistent massive changes regularly to their structure) and the ever changing nature of delivery of services through the web (meaning yet again more change to the structure of such applications) it is about painstakingly keeping up with these social media apps.
Browsers are pretty much the same issue...
It's about staying (...if not ahead of the curve) ...at the absolute worst just slightly behind the curve...or else out of pure frustration no one will use the browser ..it not providing what other browsers offer or it being too slow in compare or any of countless other issues which drive people to move on to other interfaces..

3rd-As a topper browsers and social media apps always aim their devel to run on the latest devices and withdraw support for older devices. The point is.. it is a waste of resources, manpower and money continuing support for always dwindling user numbers for old devices as they migrate to the devices which are the latest "shiny".
So owners of older devices are fighting the creators of the service / program directly ...pretty much....

So all in all... it really is a trifecta of tech progress that collides in a not-so-nice way ...

Unless you find a program for facebook interaction like ttytter which aims at the heart...the foundation ...of a program... so that regardless how the shell changes ...the program still works. It is a "forever" babysitting, diaper-changing maintenance project. Few people have the stomach or attention span for doing that....for long anyway.

So honestly the best suggestion yet again is if their is a prog, app, plugin that isn't working or isn't available ...
1-do without.
2-find someone who can fix a broken program or write one for the community
3- start writing it yourself