USA: Spanish. I’m learning Spanish, and I think as a whole it’s like 18% of people in the USA but I feel like you’re likely to encounter some Spanish speakers and make friends even if not everyone speaks Spanish here.
Brazil: It looks like Spanish is also the second most spoken language with 4% or English with around 5%. I’m sure you’re more likely to find people on the Internet who speak it.
French: English, apparently a quarter of the population speak it??? Not sure how likely you are to find someone in the wild speaking it, but on the Internet, a lot of people.
Here in Ireland, you’d be hard pressed to find somebody who doesn’t speak English. Everybody born here speaks it fluently, and immigrants tend to speak enough to get by. Yes, if you speak the official second language you will have no problems.
Now if you speak Irish, our first official language? That’s where you run into trouble. Irish is only used as a daily language in a few small areas. Since gaining independence, every government has supported efforts to revivify the language, and all have failed. Decreasingly many people speak it daily, and while many people know a few words, not many can hold s conversation in it. In fact, you’d probably have a better time speaking Polish.
(I gather this situation is similar to that in Aotearoa).