I’ve looked at this question, as my rising 9th grade son is similarly STEM focused. Here’s some information on foreign language requirements that I found:
Carnegie Mellon School of Computer Science: 2 years
https://admission.enrollment.cmu.edu/pages/academic-requirements
MIT recommends: 2 years
http://mitadmissions.org/apply/prepare/highschool
Worcester Polytechnic Institute: no requirement specified
https://www.wpi.edu/admissions/undergraduate/what-we-look-for
Santa Clara University: 2 years required; 3 years recommended; 4 years preferred
https://www.scu.edu/admission/undergraduate/first-year-students/
Cornell Arts & Sciences (home for one Computer Science major): 3 years
Cornell Engineering (home for another CS major): foreign language recommended (no min requirement)
https://admissions.cornell.edu/sites/admissions.cornell.edu/files/2017%20Freshman%20Requirements.pdf
Rice University: 2 years
https://ga.rice.edu/undergraduate-students/academic-policies-procedures/admission/