Android directory picker does not work

[lostmsu]

I don't seem to find a way to grant 3rd party apps RW access to SD card or its subdirectories.

In fact, standard Android way of selecting a directory does not work at all because "My Files" is opened for a directory dialog, and there's no button to choose directory in that popup.

Repro

P.S. I am using Material Files just as an example, any app that needs to open a directory will face this problem

1. install https://github.com/zhanghai/MaterialFiles/releases/tag/v1.7.4
2. open Material Files and grant storage permission
3. click on the 1 MENU button in the top left corner to open side menu
   
4. click 11 Add Storage
   
5. in "Add Storage" popup click 1 External storage
   
   6: My Files is opened to choose the directory, but My Files does not provide any way to say "Yes, please use this directory"
   

Extra

Even when I explicitly give any app storage permission in the settings, they don't appear to be able to write to SD card. E.g. in Termux I am able to navigate to /storage/6067-11F7/Movies/Camera and list files there, but I can't create new files:

/storage/6067-11F7/Movies/Camera/> touch new_file
touch: cannot touch 'new_file': Permission denied

P.S.

I am using HMT-1, OS build 12.6