YouTube would also be popular, in most of SEA the internet means mostly Facebook and YouTube, to the chagrin of Chinese internet services who can’t even compete outside of China in their own backyard (well, TikTok is hugely popular there, as it is here, Myanmar is also blaming TikTok and YouTube for ethnic violence, so it just isn’t Facebook). But I’m not sure how Facebooks‘s popularity equals a monopoly, they aren't engaging in anti competitive behavior, the infrastructure is free for use by competitors. The only thing Facebook puts in beyond other markets is localization and marketing.