So, why does the query exist? Because homebrew developers love limits.
Connect your 3DS to your home Wi-Fi and use an FTP client (like FileZilla) on your PC to wirelessly drop MP3s into a "music" folder on your SD card. To get the dark mode Spotify look: spotify 3ds homebrew
For those who don't want to use the specific Spotify homebrew, the community has developed several high-quality music players that mimic the experience: So, why does the query exist
Local playback of exported tracks
: You will likely need a larger SD card (32GB or higher) to store music libraries, especially if using local players like ctrmus. hShop / 3hs spotify 3ds homebrew