So I'm an old fart that still uses an mp3 player that transfers files via USB or SD card, and since changing to Linux, updating that thing has been PAINFUL due to the loss of MediaMonkey.
Absolutely none of the modern Linux music players do proper playlist-based file syncing. (That is, you select the playlists to update, and sync both the files and the playlist m3u to the target device, even if the target device uses a different file folder structure from your computer.) Rhythmbox pretends to, but in practice you can only do it once and all subsequent tries error out. Having to wipe the entire gigabytes of data every single time I want to update the player? Um, no.
The closest I got was using Strawberry to transfer files, but it doesn't sync the playlist itself, which is a huge hassle. And I know, another major old-fart moment, as the younguns these days just use cloud servers and dynamic playlists and service-based playlists and shit. Which is therefore what all of the non-dead Linux music players focus on.
But I think I have finally got a working solution, by running 32-bit Foobar2000 through Wine with the OneWaySync component.
(Although, I will still have to use a bash script to do auto-edits of the device playlist filepath, since Foobar is exporting Wine-assigned filepaths. Thankfully I already have one basically good to go from my Strawberry setup.)