Not everyone knows this so im gonna tell you. Countries that speak the same spoken language will not necessarily use the same sign language.
For example, American Sign Language and French Sign Language are related and I’ve known ASL users who have said they could stumble through communication with people who use LSF.
British sign language is completely unrelated to ASL however. The two languages have almost nothing in common. BSL is related to Australian sign language but Auslan and BSL still aren’t the same language.
Mexico from what I gather has at least three completely unrelated sign languages, though LSM is the most widely used. Mainland China and Taiwan use completely different unrelated sign languages despite both countries using Mandarin. Portuguese sign language is influenced by Swedish sign language while Brazilian sign language is influenced by LSF. In most of Canada they use ASL but in Quebec they have their own unique sign language that’s still related to ASL and LSF. Nicaraguan sign language is a unique language naturally developed by children in a school for the deaf and is completely unrelated to the sign languages around it in other Spanish speaking countries.
I could go on and on and on. There’s hundreds of sign languages out there and they don’t follow the same geographic lines that spoken ones do. Keep that in mind.