Add USB-C ports to an old 2014 iMac - Ask Different
iMac 21.5-inch Late 2015+Retina 4K 2015 Service Guide to Repairing PDF file | eBay
Satechi Aluminum Type-C Clamp Hub Pro with USB-C Data Port, USB-A 3.0 Data, Micro/SD Card Reader - Compatible with 2020/2019/2017 iMac & iMac Pro, Does Not Fit 2021 iMac (Silver) : Amazon.ca:
Amazon.com: SABRENT Multi Port iMac Hub with Front Access USB Ports, SD/Micro SD Card Reader, 3.5mm Headphone Jack and Rear HDMI 2.0 Output (iMac 2017 to 2020) (HB-SIMC) : Everything Else
Use Early 2009 24" iMac as an external for 2015 15" MacBook Pro Retina | Canadian Mac Forums at ehMac