I don’t know, I only have an instagram account so I can open posts/pics that sometimes are linked on a blog or website, and to look at that one cat account I follow when I log in once in a blue moon. No post of my own, no phone app. I don’t believe Meta knows a lot on me just via that. I wouldn’t want to lose the account just because I refuse Threads’ business model though.
“Foreign” languages communities aren’t big enough on Lemmy for people to only post in them. Most people will post in English too.