What you'll need:
Android powered headset (in my case an Oculus Quest)
Cell phone capable of casting (mine is a Pixel 4)
PC/Laptop for sideloading (I used SideQuest)
Airscreen APK (https://apkpure.com/airscreen-airplay-cast-miracast/com.ionitech.airscreen)
Shared network between phone and headset (hotspot should be fine)

Steps:
1) download and install Airscreen on your headset (SideQuest in my case)
2) run Airscreen in your headset and click start
3) start casting from your phone to Airscreen
   Pixel 4 / Android users:
     a) settings
     b) connected devices
     c) connection preferences
     d) cast
4) verify that cell phone screen is displayed in headset
5) connect phone to RC and operate aircraft as usual
6) profit

**Troubleshooting Tips**
There are a handful of Airscreen APK versions available... find the one that works for your device.
If Airscreen fails to load on the Oculus Quest verify that you have Oculus TV installed as this serves as 2D Android wrapper for Airscreen.

Hello there Spooky Spirits. Thank you for reaching out and for sharing these information and these troubleshooting steps. Just a reminder that as of the moment the DJI Mavic Air 2 is not compatible with the DJI Goggles. Thank you for your support and fly safe always.

DJI Stephen Posted at 6-16 21:25
Hello there Spooky Spirits. Thank you for reaching out and for sharing these information and these troubleshooting steps. Just a reminder that as of the moment the DJI Mavic Air 2 is not compatible with the DJI Goggles. Thank you for your support and fly safe always.

Thank you for the reminder . My method is janky... but until DJI decides to support their goggles this is one of our only options.

Spooky Spirits Posted at 6-16 23:47
Thank you for the reminder . My method is janky... but until DJI decides to support their goggles this is one of our only options.

Hi there Spooky Spirits. Thank you for the reply and for giving out these additional information. Rest assured that DJI is continuously testing multiple ways on how to improve the compatibility of the DJI Mavic Air 2. Have a safe and a happy flying always.

Hey Spooky, thanks for this post. I just got my Mavic Mini yesterday and was looking for ways to do goggle-based FPV. Thankfully I already had a Quest, and your steps worked perfect! I can now cast my iPhone 11 Pro to my Quest and have basic FPV! The quality is OK and there is a bit of lag, but it's usable for just messing around and having fun flying.

Thanks again!

ReliC Fly Posted at 8-14 10:56
Hey Spooky, thanks for this post. I just got my Mavic Mini yesterday and was looking for ways to do goggle-based FPV. Thankfully I already had a Quest, and your steps worked perfect! I can now cast my iPhone 11 Pro to my Quest and have basic FPV! The quality is OK and there is a bit of lag, but it's usable for just messing around and having fun flying.

Thanks again!

You are quite welcome... I'm still pretty desperate to find a better solution.

Wow! thank you very much for sharing this.  awesome flight millage there

Spooky Spirits Posted at 2020-6-16 23:47
Thank you for the reminder . My method is janky... but until DJI decides to support their goggles this is one of our only options.

...How janky? lol.. can you give more detail before I drop $299.00 on a headset.