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US applications as a UK student

For some context I am a year 13 student currently about to sit my A levels, and planning on taking a gap year after my exams to work and volunteer to earn some money, and build my work experience. I want to apply for university in the US as I am a citizen there, and want to take pre-med courses. I am honestly so so so confused about the whole application process, and keep hearing people talk about all these confusing terms i have never heard before.
To get into any top school in the US, most applicants have multiple awards, certificates and essay prizes under their belt, and it is still very hard for them to get admitted. Through searching and searching for anything similar of the sort that I could also complete, I saw most opportunities either require a few thousand pounds/a donation. Most free opportunities are only in the US and require you to be enrolled in high school there. For international applicants, what kinds of things did you do to maximise your chances? Also does anyone know of any STEM related essay competitions that a y13 student can take part in? Also does anyone know of any good youtube channels/videos that explain the application process well?