Music library grayed out on new iPhone after restoring from backup

Last winter, I upgraded from an iPhone 11 to iPhone 14 pro, and set my phone up by restoring from iCloud backup. Unfortunately, it appears that all of my non-purchased downloaded music (e.g. albums that I burned or had digital downloads for) is visible, but not playable, and I get the "this item is not currently available in your country or region" error when I try. Furthermore, it seems like some of my songs didn't even transfer/restore from backup, as I can see that some full albums I had are missing songs. If it helps to know, I don't have an Apple music subscription. My PC that originally held my iTunes library was wiped years ago and I never got around to restoring it, and I already wiped the old iPhone 11, so now potentially the only thing left holding my music library is my grayed out iPhone 14 pro.

I've tried connecting my new phone to iTunes on my PC (Windows 11 laptop) and viewing the iPhone's music library through there, but it unsurprisingly shows up as empty when I do. Outside of that, I have no clue how to try and fix this, if even possible. Would getting an Apple Music subscription and using something like the sync library feature work at all? Thanks for any help.