Store files securely.
Use your YubiKey to encrypt and securely store files. Download and decrypt from any device as long as you have your YubiKey with you.
Files are encrypted on the device with elliptic curve cryptography (X25519) using a YubiKey. Unencrypted files will never leave the device.
As long as you use the same YubiKey, it doesn't matter which device you use to manage your files: files can be downloaded and decrypted on any device that has the app.
No personalised user account needed. YubiKey is the only thing needed to determine which files are yours.