I have an app that downloads files and stores them in a folder in external storage. I would like to be able to open the built-in Android file manager app to show my folder to the user. Once the file manager opens, I want the file manager to behave as if the user started the file manager by tapping the icon on the home screen. That is the user should be able to copy, move, and rename files as he or she pleases. If the user taps on a file, the file manager should try to find some app that can open this file. This is the same user experience as starting the file manager manually.
I found many questions on StackOverflow, which deal with opening the file manager, but none of them fit my use case.
ACTION_GET_CONTENT is commonly recommended. For example here Open folder content with default file manager in android and many others. This does not work for my use case, because it brings up a file picker and passes control back to my app as soon as the user taps any file. I want user tapping on a file to have the same effect as if they opened the file manager manually (without my app), browsed to the file and tapped it.
I do not want to make the user select which file manager to use. I always want to open the built-in file manager, which is available on all Android devices since Nougat (https://android.googlesource.com/platform/frameworks/base/+/008e948/packages/DocumentsUI/src/com/android/documentsui/FilesActivity.java). If the device vendor or the user somehow uninstalls this file manager, I am fine with the operation failing. I do not want to complicate user experience by making them select which file manager to use.