It's a book, but there are multiple in the Final Fantasy series. The Remake in particular seems to have a few of them in Japan.
The English copy of one of them just came out and you can get a copy on Amazon:
Final Fantasy VII Remake: Material Ultimania https://www.amazon.com/dp/1646091213/ref=cm_sw_r_cp_api_glt_fabc_8CNS5EZ2074VA7RAYGY4?_encoding=UTF8&psc=1
This comes out December 28th in the USA. So those posts might have something to do with it. I don’t have Facebook so I can’t check out their page.
I can try to get it. But it may be sold out, so if you look on a search engine I'm sure somewhere else will be selling as well.
Final Fantasy VII Remake: Material Ultimania https://smile.amazon.com/dp/1646091213/ref=cm_sw_r_apan_glt_fabc_DXFPX9RXY8N20BH6EAXT
Says it won't release until Dec 28 which is a weird time to release anything, but at least it's being translated!
Looked it up. Yeah he meant this one I’m sure. I just preordered it
Final Fantasy Vii Remake: Material Ultimania https://www.amazon.co.uk/dp/1646091213/ref=cm_sw_r_cp_api_glt_fabc_ZQN6R07TVKDR298MKYE7?_encoding=UTF8&psc=1
Final Fantasy VII Remake: Material Ultimania https://www.amazon.com/dp/1646091213/ref=cm_sw_r_cp_api_glt_fabc_CDCQ6DGYQST5VK4NBBHX
It doesn't come out until December. There is a new one that's still Japanese only, called the Plus version