If you're on Desktop just use VLC, or try running Nova in an Android VM.
Most Linux users are the type to meticulously organize their files, so I wouldn't expect that there's an app that'll do what you're looking for. There are plenty that will help you rename/restructure your WebDAV though.
As much as I don't care to use Ubuntu anymore, I will always be grateful for giving 15-year-old me a comfortable and easy transition into Linux. Hard to believe that was 20 years ago, I think I still have one of the CD-ROMs they used to mail out somewhere.
Those issues were related to Covid. It made perfect sense for them to focus on their corporate clients, who are their largest revenue source. I've also never heard anything bad about their customer service, nor the quality of the products or pricing.
Now that those supply issues have been solved, there's no real reason to be wary of them. They make an incredible product at a fantastic price.
My music is stored on my real-debrid account, and I use Lidarr and Debrid Media Manager to manage it. For a player/streaming server I'm currently using Jellyfin, but I've used Navidrome and Plex in the past and found them to work great.
All my local music is stored on a NAS which Jellyfin also has access to.
edit: For the lazy there's always SpotifyX for Desktop, and XManager for Android.
This is what they've done since day one.