@clark Ugh. You could probably get away with multiple cloud storage services then, and mapping their folders to the music player of your choice. Also, use file types that are generally smaller in size for storing music (like opus or ogg). For cloud services, use the ones whose apps support Storage Access Framework so they can appear in the default Android File Manager / File Picker thing (you can also use something like Round Sync to access them all, and it does all the job for you). If you're willing to pay for cloud storage, then one single provider with 100-200 GB can also be more than enough for your music needs if you own more than just a few songs.

Then you can add the folders in your music player settings.

Edit: Don't forget to also backup your music somewhere in case something happens with your phone or your cloud provider(s)