0.20.0 - virtual media grows up
Virtual media has handed the target an image since 0.2.0. Two things you kept running into.
The right kind of drive, chosen for you. Installers expect an optical drive and a lot of them refuse to boot from anything else. An .iso is presented as a CD-ROM now and anything else as a removable disk, with nothing to set. You can still force either one when a file is misnamed, and switching re-plugs the USB drive for you.
The whole card, not one file. A new item in the Media panel hands the target the entire microSD card as a USB drive - every file on it, not a single image. On rev 3.x boards it is read-write, so the target can copy files onto it, which makes the KVM a way to get data off a machine with no network. While the target has the card the console steps off it, so there is only ever one owner, and it re-reads the card when you take it back, including when the target reformatted it.
Uploads now show throughput and an estimate, so a slow multi-gigabyte write visibly moves instead of looking stuck.