“Do US universities expect international applicants to have similar accomplishments”
The short answer is “yes”.
However, if you do one thing very well, that can be a very good extracurricular activity. You do not need to have a long list of ECs. Music can be a very good EC. Doing what you want to do very well is the right approach to take.
Also, ECs do not need to be associated with a student’s high school. Working a job, looking after a sibling, volunteering at your church, or significant musical awards or abilities are all ECs. So are many other things.
I was an international student at a couple of top US schools (one for undergrad, one for a master’s), and to be honest I was blown away by the accomplishments I saw from some of the other students that I met in international students events.