I think the best concept for file management ever invented is the one used by the orthodox file managers (Double Commander, Midnight Commander, FAR etc. etc).
This appears to be aiming at mobile, so maybe a split screen wouldn't work, but I'd at least argue that directories should be at the top.
There are cases where a file is associated with directory, e.g. you export a web page and its contents are saved within a dedicated directory, and some languages will allow module.foo and module/submodules.
But those are odd cases and the insight that the file managers had was that folder navigation and file manipulation are two separate things. If you need to move a file, you always want to move it to another folder. All the files just get in the way. If you want to find a file, it's in a folder, it's not "between" two files.
Meaning, the screen is always split in two. On both sides, there's a directory shown. All commands (copy, move, etc.) now instantly have a target (namely, the other side).
I used Solid Explorer when I was on Android and that's exactly how it was set up. I really can't think of a better design pattern for a file manager on a mobile device.
