Foobar2000 on iPhones?

I'll do my best here to not rant about the alleged "ease" "convenience!" "ecosystem!" and / or "just get a Mac!" chorus through the years.  But it's going to be hard.

Because I have just spent 2 hours with Apple tech support to no avail, trying to simply transfer a file from an email to my phone.  This was the goal:

1) Download Foobar2000 to my iPhone  (Seems to work...)

2) Download and test an MP4 music file from an email to my iPhone.

(Anywhere within my 100 GB's of free space would be fine but even this step was like putting a man on the moon.)

3) Get the Foobar app to find / locate / see and play the file.

After 2 hours, the only thing Apple was able to propose was for me to

a) reactivate my files folder / icon and to
b) download GarageBand to create a folder to receive the file.  

At last, I was able to at least see the music file in the GarageBand folder, and click on it to play, but not through Foobar.  It seems you cant drag and drop files onto the free space of IOS, but actually need a specific app and file structure to open anything and everything on an iPhone?  Maybe its time for a Samsung.

All I am trying to do is to have a lean, mean, quick playlist capable machine where I can playback WAV or other audio files, with or without access to WiFi or mobile data, without heaviness and restrictiveness of iTunes, my iTunes library, and / or any particular iTunes account and while using less battery.

I know Foobar is popular around here so thanks for any thoughts.