Scores/EC — chances to be admitted

Hello. I am a brazilian student, and I am going to apply this year.
Today, I saw my that SAT score was 1240 — a rather low score for the universities I would like to enter.
My point is: I will have the chance to take the Physics SAT Subjects, but I have totally lost my confidence and I am not sure if it will even help in my application. I certainly will not send my SAT Reasoning scores, and would like you to be honest about the chances (if I even have some) to be sucessful in my application.
I am the president of the students council, have won a state prize in a robotics olympiad, and worked as a Physics tutor for some months. I do not have biggest awards as many brazilians have, what lowers my confidence even more.
Is it possible to get accepted in a top university without great awards and top scores? (I have a good GPA). Is it worth to take the Physics test, or it will not make any difference at all?

ps: my intended major is either Computer Science or Engineering (I have not decided which one)

I don’t think the physics subject test would make much difference, but you could certainly take it. Are you planning to take the SAT again?

What is your budget?

What particular schools, if any, do you have in mind?

Do you have college options in Brazil?

Well, with nearly all the test centers being closed and tests canceled, I would have to choose between taking the SAT again or taking the physics subjects.
About the budget, I would need at least a full-tuition financial aid to attend college.
I’m interested in some really competitive schools (such as Stanford and UChicago — yes, I know it’s nearly impossible) but also other colleges such as Carleton, Harvey Mudd, Swarthmore… I know they are also competitive, but when it comes to a generous financial aid, there’s no much “safety” colleges available to international students.