Ha, no. But I’m very, very glad you responded as this seems to be a critical issue to developers that require Android expansion files.
The problem is complex, but the TLDR is that games do NOT have read/write access to the OBB directory without explicitly requesting READ_EXTERNAL_STORAGE and WRITE_EXTERNAL_STORAGE in the manifest.
By doing this, however, newer versions of Android display an onerous permissions warning: “Allow YOUR APP to acces photos, media and files on your device.” After casual research, some publishers state that this results in a 10%-15% loss of customers. (They download the game, but do not run it.)
There are some fairly lengthy threads on this subject, which I have included below for reference. While I know this isn’t really a “Unity problem”, I was hoping somebody there may have a best-practice suggestion for this situation.
Some references: