I can not tell you where to find information, I only hear about the dialysis when the trip has been organized. I have too much for a comment so I make it into an answer.

My sister in law works in a clinic where they do the dialysis, it is their only work there. They often have people coming in for a few sessions while they are staying in the country.

It takes preparation, sending your medical details before you travel, with time enough for the clinic or hospital where you will go to come back to your home clinic or hospital if there are things which are not clear.

If you travel to a country where they speak a different language, you may need to bring someone to translate for you, (which can be your host if you stay with a relative) or it can be a phone service which is on call to help you if needed.

It is very important that you can talk with the medical staff before the session. You are the one who knows what is the usual procedure and you are also the one who suffers when something does go wrong.

And their clinic often send information about patients (on their request and only with their OK on it) to other medical locations, where their regular patients will visit on their travels.

Often they are in telephone contact on the first day of treatment in the other location, to make sure there are no misunderstandings on the medical side.

As someone who needs dialysis, he is likely to be low on energy part (or even most) of the time. Which makes travel more of a burden than it was in the past. There are still options though.