I have aroued 11k files on my phone’s sdcard, and while the interface is not that polished, Fossify Music Player has been able to handle my library quite ok.

Usually, under btrfs filesystems containing system data you can get snapshots and rollback flawlessly, but some subfilesystems do not get those snapshots by default, like /var/log or /home, so you may need to set them up in order to enable snapshots, and manually create one when you start tinkering with your system. You then can revert the full snapshot, or even individual files