Android's historic feature (2.2+?) for moving apps to external SD card:

• how do I transfer apps, the whole app, onto my SD card to save phone storage space? https://support.google.com/googleplay/thread/200729283/how-do-i-transfer-apps-the-whole-app-onto-my-sd-card-to-save-phone-storage-space?hl=en

• Moving apps from internal storage to micro SD card on phone/tablet: https://old.reddit.com/r/AndroidQuestions/comments/12dwn7q/moving_apps_from_internal_storage_to_micro_sd/

• .asec: https://en.wikipedia.org/wiki/.asec

• What does /mnt/asec directory contain? https://android.stackexchange.com/questions/155565/what-does-mnt-asec-directory-contain

• Analyzing encrypted Android apps (.asec)? https://reverseengineering.stackexchange.com/questions/1876/analyzing-encrypted-android-apps-asec