This post makes no sense. The author goes from having no internet due to a bombardment to LLM'ing. I find it hard to share the plight of a warzone when they go unhinged to build their own audio player afterwards (?!). If I want a music player every OS comes with one, and phones hold enough storage. USB thumb drives are also good. Failing that, burning CDs and using rechargeable batteries is another off-the-grid solution that will work fine, and CDs are easily transportable and will last for decades. Slightly physically damaged CDs are somewhat resilient and can be brought back to life with toothpaste, so they're somewhat "better" than files which shit the bed if there is any data corruption.

The point is that the author wrote the music player app because they wanted specific features and for their own pleasure/coping.