ZUGate

ZUGate - provides access to USB drives and disk images with FAT, ExFAT, EXT2/3/4, NTFS, UDF, and ISO 9660 file systems. Supports encrypted devices (LUKS 1, LUKS 2, BitLocker, TrueCrypt, EncFS drive protection formats).

The app doesn't have permission to access the internet, so cannot transmit any information to other services or persons.

Your device must have support USB Host (OTG) for access to USB drives. Otherwise, work will only be possible with disk images.