I'm not sure, but if your concern is the visa... as far as I'm aware, people only need to acquire a visa for the USA (which is more "complicated") and automatically they have a "free pass" to watch the games on the Mexico and Canada.
I don't agree with this. Getting a visa for Mexico or Canada may not be a big deal for US/EU citizens. But if someone from China or India want to visit these countries, in order to watch the world cup matches, they still need to go through a lot of formalities. And getting a US visa is entirely at another level. For people from the third world, it is next to impossible to get a tourist visa to the US. In short, I guess the fans will be mostly comprised of EU/US citizens for the 2026 event. Very few of those from Asia or Africa are likely to travel in order to watch the matches.
What @alegotardo was explaining is that the most important Visa for the 2026 world cup is the US visa. Any fan that is fortunate to get it will have free access to watch games in both Canada and Mexico because there will be no restrictions. @Sithara007 I totally agree with your observation about getting a US Visa as a citizen of a developing nation. In my country, if you apply for a US Visa it will take close to one year and six months to get a Visa interview appointment because the process is slow and there are backlogs of applications. I also suspect that the government intentionally made it slow to reduce the number of people that might be fortunate to get Visas. The US is already a rich country so I don't think they have plans to monetize the world cup, so I don't expect this strict immigration policy to change because of the world cup.