Yes, you can apply to Harvard for a B.S. in Computer Science even when you are studying through NIOS.

Harvard University is one of the most competitive universities in the world. Admission is offered after taking a holistic review of several factors: academic performance and standardized test scores, extracurricular activities, essays, and letters of recommendation.

Here's the academic part in a gist:

High Grades: While NIOS usually has its own grading system, Harvard will review the quality of grades comparatively based on the context of your high school. Thus, an attempt should be made for an extremely high GPA or equivalent.

SAT or ACT: SAT or ACT are the standardized tests required for Harvard University. You should try to get majestically high scores in both the Math and Verbal/Reading sections.

While not required, high grades on SAT Subject Tests in math and science can be helpful.

Extracurricular Activities: Admission to a graduate engineering program requires your extracurriculars to show that you have a passion for the field. This might mean participating in programming competitions or engaging in robotics clubs and research.

Personal Statement: An interesting personal statement that informs about the applicant's unique qualities, motivations, and goals.

Letters of Recommendation: Get strong letters of recommendation from teachers, mentors, or employers to attest to your abilities and character.

Fees:

Tuition: Harvard tuition is quite high. You may visit their official website for the most updated and accurate tuition fees. You also have to pay for housing and meals.

Harvard offers a lot of scholarships and grants. There are work-study programs too available for you.

Hope this helps