Earlier quoted context omitted.
Status quo: https://www.signlvideo.xyz/
What is the source of the 700 millions number? Is that the global total? It can be a problem because each country has a different sign language.
Yes, that is the total number (World Health Organisation) of people who are deaf or have hearing problems worldwide.
And yes there are lots of different languages, which can make it hard to translate things digitally.