I took a peek into APFS a bit ago [1] because I (stupidly) yanked a usb SSD before it was unmounted and corrupted it. Reading the documentation, it seems to have many "cool" features which just aren't fully exposed/utilized in the OS, and there is a lack of API tooling.

For example: it is copy-on-write, and my corruption happened in the superblock checkpoint. There is no built-in command in Disk Utility to "mount" an older checkpoint (and accepting a small amount of dataloss). Also the "First Aid" command allegedly runs volume repair top-down when it is recommended to do it inside-out.

[1] https://www.ntfs.com/apfs-structure.htm