It won't help. Case in point: Steam. If your indie game isn't on it you can as well not release it at all, as the money you collect will be a pittance.
A better comparison is Google Play versus F-Droid. Yup. The overwhelming majority of people get their utility apps from Google Play still. However, for anyone who cares to do so, there is F-Droid, Amazon, and plenty of others that offer more than just utility apps, including Epic Games app where countless folks download Fortnite, if you want to bring it back to video games and the success or misinformed lack thereof with third-party platforms.
With the likes of F-Droid, everything on it is free, mate. It is free as in beer and free as in freedom, it's FLOSS. Money doesn't enter the equation, but everything is possible to audit.
Like I told another user: If you care about these things, the only winning move is not to play. Ergo, it's there for anybody who cares to seek it out.
Let's bring it back to games again. Fortnite was removed from the App Store. You bet that Epic Games would have released their own Epic Games app just like on Android to get iOS users playing Fortnite again. If you don't think that it would have been a huge success just like on Android then I can only laugh. So many young folks switched from iOS to Android to keep playing Fortnite.