Well, here is a US poll from March on various world leaders, and folks like Theresa May and Justin Trudeau seem to rate high enough that it presumably exceeds their numbers in their home countries:
https://uselectionatlas.org/FORUM/index.php?topic=261065.msg5580313#msg5580313But note that they included the country name in the polling, so they were testing names like “Justin Trudeau, the leader of Canada”. Thus, many respondents were probably voicing support for the country rather than the person. If you did this without such prompting, then presumably you run into the problem of leaders getting small #s in foreign countries because of lack of name recognition.
