ls /overlay/upper/usr/lib/opkg/info/*.list | sed -e 's/.*\///' | sed -e 's/\.list//'
# mount|grep ext4 /dev/mapper/pve-vm--501--disk--0 on / type ext4 (rw,relatime,stripe=512)
# ls -l /|grep -E 'overlay|rom' drwxr-xr-x 2 root root 1024 Jan 27 23:53 overlay drwxr-xr-x 2 root root 1024 Jan 27 23:53 rom