: You can find verified APKs on reputable third-party sites like Limitation
Check the Google Play Store first; if it says "unsupported," proceed to an APK mirror.
: You cannot run the latest version of the main Facebook app. You must hunt for legacy versions (often from 2021 or earlier) via third-party repositories, which are not verified by Google Play.
If you manage to install the last compatible version of the Facebook app (likely a version released roughly between 2015 and 2017), you are greeted with a vastly different experience than what modern users expect.