My understanding is that Canadian FAANG offices are staffed mostly with those who cannot (and often will never get) a US visa, plus the odd local who doesn't want to move to the US for personal or family reasons.
(I've been in that boat myself, and every single person I worked with in the office in Canada is in US today.)
Source: Canadian working in FAANG in Canada
>those non-Canadians who cannot (and often will never get) a US visa