@gardenstategal has covered most of what I would have said.
Here’s a link to a recent post about the school’s math team:
https://www.georgeschool.org/george-school-math-team-ranked-20th-in-nation/
As for academic rigor, my daughter (GS 2018 grad) is at a single-digit admission rate university and seems to be doing fine in adapting to a college workload.
I do want to comment on your question about whether the school is “too politicized”. The school (and the student body) definitely leans liberal…and this should be no surprise given the track record of Quakers in America. But part of their Quaker-ness also means that it’s a very welcoming environment. Moreso, IMO, than the average American BS. But I also think it that it’s a “meet halfway” thing…something to consider if you are going into the process with a “we’ll accept you as long as you agree with us 100%” mindset.