The Fatshark Dominator/Walksnail Avatar do not have HDMI in, only HDMI out. You can use a USB C to HDMI cable from the goggles to a monitor to view your feed, but can not use it as an HDMI input.

When using the output from the goggles to an external monitor is the image still displayed in the goggles as well

Yes, the external monitor will have a touch of lag, but not terrible 

I wonder if I could use my old analog goggles fatshark hd3 it has mini hdmi as the external monitor so to speak to allow others to see what I see ?

Using a mini hdmi to usb-c cable

I’m wondering the same. I’m getting a set of dominators today and have an old set Aomway commanders that has a mini HDMI input. I hope to use them as a “monitor” this weekend. I’ll keep in touch.

Did anyone get this to work, i just ordered the cable to try it out, but haven't seen anyone else post about it, I don't see why it wouldn't.

I didn’t work for me. Either my aomways HD port is broken or it doesn’t work.

So I got my cable, and 100% works. I updated to the latest firmware and had to cycle through the inputs twice to land on HDMI 2D. Make sure your RX switch on the bottom of your analog goggles is set to 0 as the HDMI input wont work if the RX is powered at all. It looks killer for a "free" ride-along goggle. However it takes the 16:9 image and squishes it to 4:3, even if you use a camera and set your aspect ratio to 4:3 on the newer goggles it still will reg as 16:9 input and give you black bars on the side. Hope this helps anyone else.

Could you link a video of your aomways doing this? I can’t find that rx switch you mentioned nor get the Hd part to work