@Jonah12K My friends got into both the ComSci department and others. I think you have a fairly good shot at admittance.
Some specific suggestions:
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Even self-studying new languages using resources like MIT OpenCourseWare and YouTube show a lot of dedication to ad-committees. They’ll be sufficiently impressed by that, especially if you have GitHub projects to back it up!
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In my experience, it isn’t too hard to upload new apps to the Google Play Store (you only have to pay a one-time fee of $25 as opposed to Apple’s annual $99 membership fee lol). You can either use hybrid-mobile-app frameworks like Ionic 4 or use Java. You also have the option of building progressive web apps through Ionic 4 - here’s a quick tutorial on how to do that: https://alligator.io/ionic/pwas.
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Another thing you can do is make coding tutorials or run open-source blogs, like Alligator.io (the link cited in #2) or DevTronic.
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Also, there are a ton of adults out in the coding community that can be very helpful older mentors. If there are any tech meetups or coding nights near where you live, I would highly recommend joining and networking. It’s kind of scary walking into a crowd of “experienced” adults as a high schooler, but remember that they were once like you too! Those networks are valuable and can lead you to internships/externships.
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Hackathons!! Join hackathons, dude. They’re super fun and, again, great places to meet people. Plus, even if you don’t win, the experience is super enlightening and you can still get approached by the sponsors. For example, at a Twitch hackathon I was at, my group didn’t win but was asked to join a startup incubator by UMG. (Also, hackathons always have sweet swag.
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Finally, with your coding knowledge, you can apply to intern at university research departments. Maybe even cold-email a few professors at the University of Washington. You never know!
There’s a ton you can do!! 
I hope that helps.