Facebook launched the Facebook Lite app in 2015 for use in developing countries with poor connectivity. However, people all over the world were sideloading the Lite app as an alternative to the notorious bloated regular app. You don't have to mess around with sideloads anymore, though. Facebook Lite is now available in more places like the US.
Facebook Lite includes all the basic Facebook features like the feed, posting updates, photo sharing, events, and notifications. Advanced features like games and live streaming are missing, though. Facebook Lite is smaller and less taxing on the system than the regular Facebook app, and there aren't as many complaints about abnormal battery usage.
The Play Store listing for Facebook Lite was only active for about 100 countries before today. Now, Facebook says that it wants those with spotty connections everywhere to have access to the app. That includes the US, finally. You can grab Facebook Lite from the Play Store right now. It's still on APK Mirror, too.