Mount the iso file under OS

• Windows

From Windows 8 and Windows Server 2012, Windows has integrated the feature to mount iso file directly and provided OpenVirtualDisk AttachVirtualDisk APIs which were used by vtoydump . So for these new versions, vtoydump is recommend to use.
For earlier Windows versions, like Windows XP or Windows 7, you can use imdisk to mount the iso file.

• Linux

There are 2 ways for linux to mount the iso file.

• Mount the disk, then mount the iso file

For Linux, exFAT filesystem has been natively supported from kernel 5.4, so if your distro's kernel version is newer than 5.4, you can enable this feature in kernel and mount the disk partition directly. If your distro's kernel can not support exFAT, you can use mount.exfat tool which use fuse to mount the partition.
After the disk partition is mounted, the iso file can be mounted easily.

• Mount the iso file with device-mapper

The iso file was stored in somewhere of the disk. It can be one contingous area or many discontinuous striples. vtoydump tool can print all the disk areas of the file in dmsetup table format.
So you can use dmsetup to create a device-mapper block dev mapped to the iso file and then mount it.