External display issue with iMac M3

The new iMac's only support one external screen.

see > Connect an external display to your iMac - Apple Support

and "Video Support" at > iMac (24-inch, 2023, Four ports) - Technical Specifications - Apple Support

Yes, but you said "However, there may be a work around if you use an external Dock"

AFAIK, none of OWC's docks support DisplayLink. They all work with the native video support that the host Mac or PC offers, which means that an OWC Thunderbolt dock that would support two monitors in connection with a M3 {Pro/Max} MBP will support at most one monitor in connection with a 24" M3 iMac.

I believe the OWC USB-C Dual HDMI 4K Display Adapter with DisplayLink is the only "workaround" product that OWC sells. (SonnetTech sells a pair of similar DisplayLink-based workaround adapters: one that has twin HDMI outputs; one that has twin DisplayPort outputs.)

It has HDMI ports, but no other data ports (USB, Ethernet) and no memory card reader.

You were provided incorrect information, current (2021-2024) 24" iMacs support 1 external display. You can easily verify this by checking the Tech Specs of your iMac, located at iMac - Technical Specifications - Apple

However, there may be a work around if you use an external Dock. I strongly recommend contacting www.macsales.com (call them!!) and see if one of their docs can help.

I don’t think any of OWC’s docks would work around this. They all seem to rely on a computer’s hardware display support.

However, OWC does sell a DisplayLink-based dual HDMI adapter.

No, a HDMI splitter will NOT work. I told you what you need. Please contact OWC.

This is why I suggested the OP call OWC!!