Onscreen keyboard needed for iMac setup

Most any USB keyboard will work for setup, if do not have a working wireless keyboard and mouse.

Personally I keep an inexpensive Logitech MK120 set around to use and troubleshoot my Mac's.

https://www.logitech.com/en-us/product/desktop-mk120

Hello,

Please refer to the following Apple support document.

Accessibility Keyboard