I know a few people that are about to head to international co-ops. In general, they usually pay for housing and food explicitly and then don’t pay beyond that. Travel as well is common. I know of one in CS that does pay beyond that, but in general, co-ops pay much better in the US. Of course, you get an amazing experience abroad and that is usually the primary factor for those that choose to do one.
Not that many participate due to the plentiful other abroad options like dialogues and traditional study abroad. It is certainly common enough, though. The international co-op process starts earlier due to travel planning, passports, and other logistics, and there are many NEU events that try to recruit students for them. I get about 5 or so a semester about global co-op events and deadlines, even though I have never expressed any interest for them.