With Android 6.0, that changes. There is now a (very) basic file manager built right into Android. To access the file manager, ... this is handy to have when you need to poke around the file system.

UPDATE: It seems like Google changed its mind. EXT4 and F2FS will also be allowed, according to Mishaal Rahman. The EROFS file system format could help save storage space on Android 13 devices ...