Important VMs in USB

[Frozentime345]

If I put my important VM's in a usb and remove it/restart the system
what remains in the device itself? Like if an "attacker" had access to
the device later(possibly unlocked) would there be tons of information
on the device?

Also, would I be able to easily connect this usb to dom0 I assume and
reroute the port or whatever back to the usb qube after removing?

[Frozentime345]

I'm interested in drawing out characters as a method of invisibleish
input on either a touchpad or touchscreen since I want to bring my qubes
device anywhere. I couldn't find any mention of this in a fedora google
search or a qubes search nor in qubes settings. I doubt it exists but I
just thought I'd ask lol.