Thanks for following up. Free Basics is the only one I remembered, but as you said it looks like there were multiple efforts. Your Smart link is good evidence that it's ongoing at some level. I don't know the carrier business, but to me it seems unlikely that a carrier would offer free Facebook access without getting something back from Facebook.
Here are a couple articles describing it in PH[1 and 2].
It's not some limited access thing, it's literally unlimited data. Video calls, watching movies via FB, etc.
AFAICT it's still a thing, though it's not clear to me if FB is still sponsoring it or it's some carrier marketing[3].
1 - https://nymag.com/intelligencer/2018/09/how-facebooks-free-i...
2 - https://technology.inquirer.net/30705/globe-telecom-to-offer...
3 - https://store1.smart.com.ph/addons/4569/