How can I prove I play the piano proficiently to colleges?

Started to ask myself this question as I was compiling my ECs for this year. I have played the piano for 9 years under the direction of my uncle and then by self-studying. Unfortunately, my old school was too small to have much of a music program and the school I transferred to had already secured their pianist for Jazz Band by the time I arrived. So, with no school-based opportunity, is there another way to prove colleges that I know how to play beyond a basic level? Do they even care?

(Note: My technique is admittedly unrefined considering how long I’ve been playing. Because of that, I dislike entering competitions and have had mediocre results in the ones I have entered. For example, at my state Chopin competition I finished 11th out of about ~20-25 pianists. Not terrible, but not noteworthy either.)

So far, all I have is:

AP Music Theory- 5
Senior Home Performances

You don’t

No. Unless your ability is on par with a student seeking admissions to a conservatory, colleges will not care about your skill level.

You can still include your piano as an activity on your app. I know some colleges allow supplements where you can submit videos of your playing. If piano has been your main EC over these past years, I highly recommend doing this.

Why don’t you do syllabus? All strong piano students should reach Level X syllabus with distinction ASAP. Most get it around age 15, although many of my cohorts got there by 11 or 12.

There are level skill tests all over the country. Nevertheless, it may not be that important if you do not win any state level or above award. Almost everyone can reach level 10 by college application anyway.