I am looking for a way on how and where I can put and edit files that are accessible independently of the currently active android user.
I am working on Android Automotive but I think this does not matter.
Why would I want this? Imagine a big database that is shared across users.
Android explicitly mentions the BlobStoreManager but it is unclear to me how the data can then be shared between users.
You should be able to use
/sdcard/Android/obb. Please refer to this answer.