Usb qube dilema , single ps/2 port


I am currently setting up qubes on a motherboard with one ps/2 port which i would like to allocate for the keyboard.

I have one ps/2 mouse and a type A to ps/2 female active adapter which would allow me to connect the ps/2 mouse through a usb port.

To achieve without using the mouse proxy method i will release one usb port / controller back to dom0 just for the mouse function.

1. Is there is a risk of the firmware of a ps/2 mouse infiltrating dom 0 if attatched through usb port ?

**2.**Is there any risk of the ps/2 usb adapter itself infiltrating dom0 ?

I understand the risk outside of my own devices potentially being tainted that someone could plug a device into my computer while left unattended but i have solved this issue by building my entire machine into a locked steel enclosure meaning there is no possible way for someone with physical access to my workspace to access any usb ports on my machine. ( i am the only person who can plug in a usb device as it would be under total lock and key. )

So my question… Will a qubes machine with a usb qube and a single controller allocated to dom0 with a ps/2 mouse + ps/2 usb adapter attatched + physical security of usb ports give me the same security as full usb qube with all controllers attatched ? The only person who can utilise the usb ports are me due to the security enclosure i have implement on the computer itself. So i think its just a question of wether my ps/2 mouse and ps/2 usb adapter are trusted as they would be only devices utilizing a usb port on the entire machine…

Thanks you for any replies in advance.

you can have more than one sys-usb. So you can clone sys-usb, name it e.g. sys-usb-mousse and atach one USB controller (and assign the other OSB controller to sys-usb)
In this case you do not need to assign USB to dom0.

not sure I follow, but I believe using PS2 adds security, not vice versa.

and I had an experience where one USB mechanical keyboard would not work, apparently not all keyboards will Fwiw.

there is always the risk, which happpened to me early in Qubes, which was locking myself out of Qubes, because I was using sys-usb for my keyboard, and having to reinstall

yes, PS2 is always better. I it less likelly to be an atack vector, If you use PS2 you don’t need to deal with USB in dom0.
If you have one PS2 port, you can use it with your keyboard. then you can use a USB mouse.
USB mouse is much less problematic than USB Keyboard.
But if you want to improve security you can create a usb VM that has only the USB controller that you use for the mouse.