How do I write to the SD card on Nougat/Android 7.0 (VR friendly)?

Question

I'm looking for a way to make my VR Android app (for Samsung Galaxy S7 and S9) able to write files to the SD card (e.g. by downloading a .zip file and unzipping it there).

The app is mostly going to be used by people, who don't know a lot about Android/smartphones and don't want to have to deal with anything complicated (not necessarily seniors but close enough), that's why I want to make it as easy as possible for them, which also includes making choices myself (and setting it up for them) instead of showing complicated dialogs.

Special requirements:

• The files must not be deleted when the app is uninstalled - that's why I can's use getExternalFilesDirs() (Storage Volume).
• The folder everything happens in has to be easily accessable, so the zip files can be transfered to the SD card on your PC too (instead of downloading them through the app in case they are too big) without having to go down a huge amount of levels and remembering a long folder path.
• Using Storage Access Framework isn't a good alternative either because not only is picking folders nothing that's especially VR friendly but it also requires knowledge about folders most of the users simply won't have and/or won't want to deal with every time they open my app. But: If there was a way to only show this once (on the very first start after installing the app) and maybe even set the root folder to the folder I chose, so the users only have to hit "accept", that would be worth a try (unless there's an easier way).

Yes, I did set the android.permission.WRITE_EXTERNAL_STORAGE permission and also enabled the "force allow apps on external storage" developer setting but trying to write to the SD card still throws an "Access Denied" exception.

Are there any others ways to write to the SD card that are VR friendly?