Just because introverted people, by definition would prefer their own company, enjoy a quieter life and avoid crowded spaces as much as possible, doesn’t mean that they are not interested in playing a musical instrument. Introverted does not mean boring and lacking social skills, it just means they would prefer to be with people in small groups rather than large social gatherings.
I think the piano is perfect for introverts because the piano isn’t necessarily a noisy instrument, it can be played loud but it can also be played quietly. This is not true of many instruments. Electric pianos would be even more ideal for an introvert, because a person can plug in headphones to hear themselves play and block out the sound of everyone else around them.
Pianos are a great solo instrument, which means that you don’t need other people to make music with. A person can have a full and complete sound, without any other instrument, almost like an orchestra, where you can have melody lines, chords to add richness and fullness to the sound and even rich, resonate bass notes from the low notes on the piano.
This differs greatly from a lot of musical instruments that can produce one or two notes at any given time. All woodwind and brass instruments can only produce one note at a time. Violins and other stringed instruments that are related to the violin can produce a maximum of two notes at a time. Guitars can produce as many as six or sometimes twelve sounds at the same time but with guitars, it is usually chords or melody or a bass part that they are playing. A piano can play many notes and cover melody, chords and a bass part all at the same time. Pianos can literally play it all, so they don’t need other instruments and therefore other people to make music.
Many instruments can showcase their best through the context of an ensemble, whether it be an orchestra, a rock band, a big band, marching band or any other grouping of instruments that you care to name. I have discovered in recent years through my own kids playing woodwind and brass instruments that they not only get the most out of their instruments by playing and rehearsing in a band but that they actually prefer doing their practices in a group setting rather than on their own. This would not be ideal for an introvert.
Unless they are a professional concert pianist, most piano players that enjoy performing either do solo performances or they are playing in a group context where the function is not to be the soloist and not to be the centre of attention. Even when it is just a piano with one other instrument, including voice, the piano part is the accompanying role, again not the soloist, not the most important part. For an introvert who enjoys performing, this would be ideal for them.
So if you are an introvert and would love to play a musical instrument, I would thoroughly recommend learning to play the piano because it would be very suitable for an introverted person.