There are many routers that support Facebook Wifi hotspot feature. Is it somehow possible to use it with OpenWrt?
It basically allows users to use internet after they have checked in your FB page.
More info here https://www.facebook.com/facebook-wifi
There is a discussion on this topic on the forum archives as well as a Github project for it. Both are probably thoroughly outdated, but the gist is: you would need the Wifidog capture portal package and an own webserver.
To put it in agreeable terms: given it's
expletive Facebook and its security and privacy implications, I don't think anyone concerned with the furthering of open source has spent effort on this in recent years.