Thanks! it turns out that it is all there!

I never bothered to setup a YT Music account, so I never realized that the uploaded music was still available. I know this is a very niche problem, but just in case anyone is searching and comes across this:

1. Yes, Google Music uploads are saved in your YouTube Music files. You already have a Google account, so you can set it up with the same login to gain access to the files.

2. On desktop, open "Library" on the left -> select "Uploads" tab at the top.

3. Sort by "Album," "Artist," or "Song" to see the entire library.

4. When searching, etc., it will default back to the YT Music streaming service. Manually select the "Uploads" tab after each operation.

It is also possible to download your music library (although not individual songs, etc.) from YT Music, although it is not obvious.

1. Navigate to https://takeout.google.com/ while logged into the same Google account.

2. Click on "Deselect all" (unless you wish to download ALL of your google related data.

3. Select "YouTube and YouTube Music" at the bottom of the list

4. Click "All YouTube data included," then select "music-uploads" as well as "music-library-songs" (if you have any music acquired through Google)

5. Follow the prompts to receive your files. You can choose to repeat this process as a periodic backup, or a one time download as a .zip (or set of .zip files). You can download them to your PC via email link, or you can have them directly transferred to another cloud service (Box, Dropbox, Google Drive, and OneDrive as of now)

6. This process can take a while, but in my case I received the download links within a couple minutes (about 30 GB).

Good luck, and enjoy!