I mean… I downloaded a third party app from the play store. Isn’t that how you got yours too??
I mean yes, you can get third party apps on the Play Store (I got mine off F-Droid but that’s besides the point), but for most people, if they want to install “Reddit” on their phone, they’re gonna search for “Reddit,” and then when the first thing that pops up is the official app, they’ll install that, and never think twice about it.