Hello hellow, as requested... I'm responding in this thread. I do see the the USBHDD from the psutil.disk_partitions output.
"sdiskpart(device='/dev/sda1', mountpoint='/USBHDD1"
print psutil.disk_partitions(all=True)>>> print psutil.disk_partitions(all=True)
[sdiskpart(device='/dev/root', mountpoint='/', fstype='ext4', opts='rw,noatime,data=ordered'), sdiskpart(device='devtmpfs', mountpoint='/dev', fstype='devtmpfs', opts='rw,relatime,size=469756k,nr_inodes=117439,mode=755'), sdiskpart(device='sysfs', mountpoint='/sys', fstype='sysfs', opts='rw,nosuid,nodev,noexec,relatime'), sdiskpart(device='proc', mountpoint='/proc', fstype='proc', opts='rw,relatime'), sdiskpart(device='tmpfs', mountpoint='/dev/shm', fstype='tmpfs', opts='rw,nosuid,nodev'), sdiskpart(device='devpts', mountpoint='/dev/pts', fstype='devpts', opts='rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000'), sdiskpart(device='tmpfs', mountpoint='/run', fstype='tmpfs', opts='rw,nosuid,nodev,mode=755'), sdiskpart(device='tmpfs', mountpoint='/run/lock', fstype='tmpfs', opts='rw,nosuid,nodev,noexec,relatime,size=5120k'), sdiskpart(device='tmpfs', mountpoint='/sys/fs/cgroup', fstype='tmpfs', opts='ro,nosuid,nodev,noexec,mode=755'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/systemd', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/devices', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,devices'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/net_cls', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,net_cls'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/blkio', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,blkio'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/cpu,cpuacct', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,cpu,cpuacct'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/cpuset', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,cpuset,clone_children'), sdiskpart(device='cgroup', mountpoint='/sys/fs/cgroup/freezer', fstype='cgroup', opts='rw,nosuid,nodev,noexec,relatime,freezer'), sdiskpart(device='systemd-1', mountpoint='/proc/sys/fs/binfmt_misc', fstype='autofs', opts='rw,relatime,fd=22,pgrp=1,timeout=0,minproto=5,maxproto=5,direct'), sdiskpart(device='mqueue', mountpoint='/dev/mqueue', fstype='mqueue', opts='rw,relatime'), sdiskpart(device='debugfs', mountpoint='/sys/kernel/debug', fstype='debugfs', opts='rw,relatime'), sdiskpart(device='tracefs', mountpoint='/sys/kernel/debug/tracing', fstype='tracefs', opts='rw,relatime'), sdiskpart(device='configfs', mountpoint='/sys/kernel/config', fstype='configfs', opts='rw,relatime'), sdiskpart(device='/dev/mmcblk0p1', mountpoint='/boot', fstype='vfat', opts='rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,errors=remount-ro'), sdiskpart(device='fusectl', mountpoint='/sys/fs/fuse/connections', fstype='fusectl', opts='rw,relatime'), sdiskpart(device='/dev/sda1', mountpoint='/USBHDD1', fstype='fuseblk', opts='rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096'), sdiskpart(device='binfmt_misc', mountpoint='/proc/sys/fs/binfmt_misc', fstype='binfmt_misc', opts='rw,relatime'), sdiskpart(device='tmpfs', mountpoint='/run/user/1000', fstype='tmpfs', opts='rw,nosuid,nodev,relatime,size=94812k,mode=700,uid=1000,gid=1000')]
>>>