The team of developers at Facebook s it took 5 years to implement a function that has existed since iOS 9: the SplitView.
It is now possible to use the app open on the split screen with other applications on the iPad.
The latest app update allows you to split the screen with other apps, or view it as a side panel of the Slide Over. These functions are exclusive to the iPadOS and do not work on the iPhone (at least at the time of this writing).
The Facebook application can be downloaded for free from this link.