Yes. NextD Player has two USB 2.0 ports that can be used to connect external hard drives. The destination path for the external drive is typically /mnt/usbhost/Storage01/
The full list of natively supported file systems are:
sysfs
rootfs
bdev
proc
cgroup
tmpfs
devtmpfs
debugfs
securityfs
sockfs
pipefs
anon_inodefs
rpc_pipefs
devpts
ext3
ext2
ext4
cramfs r
amfs
vfat
msdos
iso9660
nfs
cifs
ntfs
fuseblk
fuse
fusectl
udf
functionfs
To support additional file system such as exFAT (some SD cards) and HFS+ (Mac), you can install the Paragon exFAT, NTFS & HFS+ app on NextD from the Google Play Store.