Until a decade ago I was one of those blind Apple users that was using iTunes as the only way to organize my music.

Now I've liberated my collection using navidrome and/or direct syncing the whole library via syncthing.

Today I noticed that I have about 20 m4p files that can't be played with anything. Seems like one day I was drunk and I purchased an album on iTunes, so I guess it's DRM.

There's a way to convert those files to something with more freedom?

I don't have iTunes but in some box in my garage I have a 15 years old iMac with some ancient os version that can't be updated because Apple's marketing team said I should buy a newer one