TLDR: A built-in img/iso mount option for KDE Dolphin would a amazing! There are extensions, but they are not easily found if you don't know what you need and feel sketchy without checking the source.

Story time:

My dad bought an old spectrum analyzer for analog audio work he does. An amazing device running ms dos.

He replaced the floppy drive with one of those compatible USB modules.

Sadly it wasn't totally straight forward for him to mount the resulting .img files in #kde dolphin.
I ended up installing an extension for it after checking it's source and that works. However, it doesn't show in the side panel and has to be found in the directory udisks uses for its mounts.
It would be a very nice feature to have built in dolphin! @kde

#audiophile