spacefm is multipanel desktop-independent file manager. It supports icons on the desktop and also can be used to create dialog boxes for the shell scripts.
By default, it doesn't contain any virtual file systems. It is design decision rather than missing functionality. Authors think that anything managable by file manager, should be mounted into real filesystem and be accessable by shell commands as well.
spacefm supports different tools for mounting removable and/or remote filesystems. Recommended one is udevil.