Photos app for offline storage is also woefully neglected by Apple. They don't really design it for use with an external drive (you are expected to locate your library on a internal storage or permanently attached storage). The reason is that the photo library constantly gets corrupted on external drives, forcing a long rebuild/repair process.

Often the photos app doesn't even detect the iphone even when plugged in, and it's a serious bug that Apple has neglected for years.

> What about the Photos app on MacOS if you have one?

If you ever try a large-scale import/export into macOS Photos be prepared for 100% CPU, endless spinner cursors and the process ending up killed because it ran out of memory.