Meta ended support for Android 4.x several years ago. Even if you find an old APK (e.g., version 318 or earlier), it will likely:
The Facebook app is available for download on Android devices running on version 4.1 and above. Since Android 4.1.2 is a Jelly Bean version, it is compatible with the Facebook app. Download Facebook For Android 4.1.2 BEST
: If apps fail to load due to server-side changes, using a lightweight browser to access m.facebook.com Meta ended support for Android 4