How to eject a USB device (no icon) from a mac to be used in VM

Use the subprocess module in the standard library:

import subprocess
subprocess.run(["ls", "-l"])

The advantage of subprocess.run over os.system is that it is more flexible (you can get the stdout, stderr, the "real" status code, better error handling, etc...).

Even the documentation for os.system recommends using subprocess instead:

The subprocess module provides more powerful facilities for spawning new processes and retrieving their results; using that module is preferable to using this function. See the Replacing Older Functions with the subprocess Module section in the subprocess documentation for some helpful recipes.

On Python 3.4 and earlier, use subprocess.call instead of .run:

subprocess.call(["ls", "-l"])

No, there isn't. Under Linux you may use HAL or DeviceKit-disks D-Bus interfaces. Note those are optional components and may be absent. HAL is older and DeviceKit-disks is newer implementations, with DK-d replacing HAL.