Hi @barnesytunas, thanks for writing.
Artists, Publishers and other copyright holders can add their content to Spotify but, as Spotify don't hold any copyright themselves and only receive the license to add content, they can't really add tracks or other content on their own.
The content you don't see available on your end has a strict relation to licensing agreements.
On the other hand, you could contact the creator of the content through their artists' label on social media or their site and ask them what their thoughts on uploading to Spotify are!
Aside from that - the local files import is still a valid workaround. 🙂
Let me know if you have any other questions!
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Note: I'm not a Spotify employee.