I'm using an old wired Apple keyboard (plastic keys) with my 2014 iMac. It had originally been used with a 2008 Mac Pro. It works without problems. I also have a more modern wired Apple keyboard with metal, chiclet keys. It works fine but I prefer the feel of the plastic. IMHO, any wired Apple keyboard should work.
Jon
macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365
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