I do it similar to you, except that I use PlexAmp for my music.
But I have to note that you and I are the exception. The VAST majority of users are, I think, doing it through, if not the Play Store itself, then some other service (e.g., Spotify).
That said, though, at least we have this option. But is there any reason that an iPhone user can't just use PlexAmp like I do? I'm pretty sure that Firefox is available to them as well.
My understanding is that Firefox on iOS is substantially limited from Windows and Android. Like they can only run uBlock Origin Lite and many add-ons aren't available. Something about Apple policy blocking browser extensions that can run scripts/code, as it might compete with Apple's app store. But that's just what I've read online from other people. It also might be somewhat different recently in the EU, at least about the installing alt app stores. As I said, I haven't used an iOS device in over a decade, so have no first hand knowledge.
But I have to note that you and I are the exception. The VAST majority of users are, I think, doing it through, if not the Play Store itself, then some other service (e.g., Spotify).
That said, though, at least we have this option. But is there any reason that an iPhone user can't just use PlexAmp like I do? I'm pretty sure that Firefox is available to them as well.