Chance me for Brown PLME?

*currently in junior year *
35 ACT
SAT: 2280
3.8 GPA Unweighted (low freshman, ~got 4.0 sophomore year and expecting 4.0 this year)
Taking AP Chem, AP Bio, AP Calc AB this year, took AP Comp Sci last year, taking AP Physics C, AP Gov, AP Calc BC, AP Stats, AP Spanish next year

Volunteer: I’ve done around 100 job hours + volunteer hours combined, but no medical related, which I’m planning to do. Is 200 hours good for medical related volunteering?

Main EC: Chess
Current National Champion for my grade, state Champion, president of school chess club, head coach of school chess club, founder of chess club for school which won 1st Team (very huge accomplishment considering my school is not very good academically, going against top academic teams- hope to write this in my essay showing my leadership and ambition)

SAT Subject Tests: Math 2: 800, Chem: expecting 750+,

I’m planning on preparing for the USA Biology Olympiad - does that help a lot? How far do I have to go to be considered “impressive”?

Any other suggestions?

Thanks!