Linux Mint Spotify flatpak how to load local files?

[Mince]

Plan

Premium

Country

USA

Device

MintBox Mini 2 Pro + 250G outboard SSD + 128 GB Flash Drive (ext4) added late summer ’24

Operating System

Linux Mint Cinnamon 21.3

My Question or Issue

Does Spotify's FlatPak allow me to use my own files?

I use Spotify on my Samsung Galaxy A54 phone (Android 16, One UI 8.0), but to use local files, I need to add them in my Desktop app, download the playlist to my Desktop hard drive, then sync the playlist to my phone over my WiFi.

I run Spotify Lossless on the phone, so I bought a cleaner copy of the Ink Spots' Address Unknown in FLAC format.

I have unjailed the Spotify FlatPak so I can read files, but the FLAC file is greyed out.  I converted it to 320k MP3, but that, too, is greyed out.

Spotify doesn't have my preferred version of Grupo Pasion Musical's version of De Niña a Mujer, so I've also bought the FLAC copy of that track.

I see there is an unofficial Spotify AppImage, and I can give that a try.

Otherwise, my Spotify Linux Desktop seems to do as it is supposed to.

There is a system Spotify app in my repository, but it requires an upgraded library.

Interestingly, the round Spotify logo that I see on my phone is on the FlatPak, whereas I have a square drab olive-green logo on the system app.  I like the aesthetics of the round logo.

Thank you!