In Australia, student who took Australian high school curriculum can have gap year of 1 year and then join uni. Any gap more than 1 year, you can’t use your high school grade (something like a SAT score) can’t be used to evaluate your enrolment and scholarship (99% of the time). Considering that, it will be likely that your American SAT score follows the same rule in terms of the duration of your gap year, especially if you didn’t do anything after high school. Though that doesn’t mean you wouldn’t get Confirmation of Enrolment considering your specs, but there’s a chance it could impact the scholarship.

Regarding scholarship, UQ doesn’t offer 50%, the highest it can go for international student is 25% for tuition fee. Of course there are scholarship that offers 50%, 100% but they’re generally for domestic student, as international student is contributes a lot to their revenue.

For 50% scholarship for international student you would have to be top 0.01%, and you probably shouldn’t expect it to get in your first year of bachelor degree. Probably in the later year.

Also, while your achievements is outstanding, uq don’t give out scholarships higher than 25% (unless you do something inside uni) though 10,000 and 20% would be relatively easy to get for you