Going by google search hits which are pretty much conclusive Golovkin: 4 110 000 Canelo: 17 700 000 Pacquiao: 19 600 000 Khan: 62 800 000 Anthony Joshua: 122 000 000 Kevin Johnson: 491 000 000
I don`t think AJ is well known in the rest of Europe but he is well known in Britain, I don`t know how many countries in Europe have access to his fights and those countries only know fighters from their homeland, beating Wlad would have got a lot of views in Germany though because that`s where Wlad had most of his fights and was well liked there too.
Mike Tyson was a global superstar too, people in Britain started called the staff dogs Tyson because of his menacing look.
Frank is out of hospital & home now but needs lots of rest. He was in hospital in Banbury The Horton general my birthplace. My family let me know he was there
Hard to say without actually living in another country to know how well known Joshua is, though I don't think he'll be as well known as he is in the UK, but then very few sports stars are as big as him in the UK. Looking at the wiki page for Joshua/Parker that fight was aired in 37 different countries/regions, many of them in Europe. Though that was a unification fight, him fighting someone like Miller might not get the same interest. https://en.wikipedia.org/wiki/Anthony_Joshua_vs._Joseph_Parker