New Picade 10" downgrade to RP3

I just received the new 10" USB -C Picade kit. I have a lot of Retropie content and since Retropie is not ready for the PI4, I was wondering is it possible to temporarily downgrade the kit to use an RP3. Would I need to locate a new X HAT for Rp3 or maybe the pi and XHAt could be powered separately? Would the cabling work? Still learning about HATs.

You should be able to use the USB C Picade X Hat witha Pi 3B. The 4B and 3B have the same GPIO pinout. I’m pretty sure its already been done a couple of times on this forum. For the very reason you state, Retropi not being ready for a Pi 4B.
You’ll need a Pi 4B USC C power supply to power the Picade X Hat though. Or the Pi 3B power supply and a USB C adapter. I used this adapter with the older supply to power my 4B.

You may also need a different HDMI cable to hook up the display. The 3B has a full size HDMI while the Pi 4b uses Micro HDMI.

Thank you for your helpful response.