[PlutoIsAPlanet]

Ventoy and flash tools should in theory support img files just fine, if anything for virtual machines img files should be easier to boot than ISOs (don't need to emulate a CD drive)

Modern Linux ISOs are a sort of hacked hybrid ISO/IMG, where keeping support for burning to CDs (the ISO part) has some trade offs (such as workarounds needed for persistence storage, multiple partitions).

[gertop]

"In theory" being the key word here. For whatever reason, it's a pita to use raw images with both virtualbox and VMware. You have to resort to third party command line tools to convert the image (qemu-img).