Would having a prominent recommender help applications to US universities?

[Sweetgum]

You might want to read this thread to temper your expectations:

Rejected by 12/13 colleges, 1550, 4.0, & 20 college classes [including college junior level math]

College classes: Calc. series (4 classes, 3 on trimester system, 1 on semester, through vector calculus) Differential equations Introductory Linear Algebra Intro to mathematical reasoning Linear Algebra (abstract vector space proof edition) Euclidean and non-euclidean geometry Mathematics with applications in the natural sciences (applied math course, goes over common modeling techniques, differential equations, markov chains, etc.) Abstract Algebra (groups, rings, fields, cosets, field extensions, etc.) 2 English composition courses 1 macroeconomics course 1 Shakespeare class 2 CS classes 2 US history classes 1 comparative politics class AP classes: Just AP Human Geography, 9th grade. My school doesn’t have many AP classes, and in that one the teacher covered less than half the material they were supposed to, even making exceptions for COVID. Got a 4 on that AP test. SAT 1550, 800 math, 750 english, 1 try. Been to multiple national and international competitions (VEX Worlds, Nat…

There are many wonderful colleges in the US that would welcome a homeschooled/unschooled international student who can show some qualifications like a SAT or ACT score. The schools you listed are just super selective about who they accept. You need more than a letter of recommendation. If you want to tell us more about what you want to study and how much your family can afford we can make some suggestions for other schools that might work for you.