I'm definitely not a good enough skater to know all the requirements to compete, especially at high levels. But.
Because of the pandemic, many countries won't let anyone in. Also, most of the skating rinks, skating events, and opportunities to skate aren't open, and most of the skating coaches aren't teaching - at least not in person.
Some estimates say this will be true for 18 months or so, some say a few months. Either way, moving right now will be a challenge.
Perhaps the national governing bodies of skating alejeather mentioned could help you figure out whether it is possible to come in now at all, and skate. If you hope to compete at the highest levels, you might also want to contact elite level coaches in those countries to get their opinion on such things, because they often work with foreign students.
And find out whether you need to obtain citizenship before competing at the levels you hope to skate, in each country, and how hard that would be to do. rules might be looser in some places for pairs and ice dance, if one of the partners is already a citizen, but I am not sure.
Also, you might want to get an estimate from the coaches of the total costs involved to live in the area, skate there, and train with them.
Many - perhaps most - high level coaches require you to audition to become their student. I don't know to what extent that can be done using videos.