One way to make a system like this work is heavily proxy and strip rich media out of the network (Globalstar sells a device called the SatFi that does this for their MEO constellation, Opera Mini used to do it for featurephones), so you can support quality of service in a remote population.

There's a financial incentive for Facebook to provide access to a specially crafted 'walled garden' that's designed for lower bandwidth scenarios. Facebook has tried this shit before in India without touting special network hardware and it was not well received: https://www.cnet.com/news/facebooks-free-basics-internet-ser...