Open vault in Android storage on PC

Use case or problem

While taking notes at work, on my company laptop, I do not want to store my vault locally in the laptop. Hence Obsidian Sync is also not an option for me.
Therefore, I’ve set up the vault in a USB stick plugged in the the company laptop, so that I can physically remove any time.
I still don’t feel secure as the USB stick can be lost and the files are not encrypted nor recoverable.
I came up with the idea of setting up the vault in my Android storage, and use the PC to access the vault via cable and enable file transfer. While I can access the mobile storage with File Browser, the storage is not visible to Obsidian vault opener.

Proposed solution

I need a solution for Obsidian to access my Android phone storage, where I can store my vault and gives my the option of backing up my vault files in private cloud and wipe the phone when lost.

Current workaround (optional)

Having the vault on a USB stick, which is not really secure.