In bios if you have an option along the lines of "legacy USB support" then your in luck as it'll treat the keyboard as a PS/2 device.
Male PS/2 to USB devices do exist but I've never used them so not sure how compatible they are.

I'm also not sure how compatible the keyboard is either? Most modern mice are now just "HID" devices and dropped PS/2 compatibility. I wouldn't be surprised if keyboards are the same

I've still seen a few modern USB keyboards around that still support PS/2 using one of the little passive purple USB-PS/2 adapters (need a purple one, not a green one - keyboards vs mice use different pins). But it's hard to find info about which ones do or don't, and sometimes you need to enable it using an obscure keyboard shortcut.

I recently found out that my Niz x87 electro-capacitive keyboard can have PS/2 compatibility enabled by holding Fn+Backspace for 5s. I actually used it a few times when my normal PS/2 Model M was unavailable… or just too loud.

Another interesting thing is that some KVM switches actually support PS/2 input device emulation. An example is the Iogear GCS1804 - you can plug a USB keyboard/mouse into it, and if you get the PS/2 cablesets (sold separately) to go with it, it'll translate the USB input devices to PS/2 for you.

kepstin wrote on 2022-10-18, 18:27:

...need a purple one, not a green one - keyboards vs mice use different pins. ..

There is no difference between passive USB->PS/2 adapters for mouse/keyboard:
Re: Any difference in usb to ps/2 adapters.

Re: USB to Serial Mouse using the Pi Pico!

I think this may be able to help? Converts to serial. And ps2?