I have a cheap set of googles that work with it....that I bought for $10 on eBay. Find ones that offer a large field of view. Mine are supposedly 120 degree.... however 100 to 110 degree field of view is more typical. The app and many other people recommend Homidio 2 glasses for their quality but they are much more expensive.
As for what you need.... that is about it. You need a long cord that connects your phone to your controller because the phone is now on your face. I actually set up the DroveVr while sitting in my house with the drone on a table because you need to adjust a few things to give yourself a good image. When you fly bring a chair too sit in because it is very disorienting at first and you will be wobbly if you stand. Legally you need a spotter to maintain VLOS.... sight to the drone.
The temptation will be to fly it off to get the full experience, but instead you want to get your bird in the air high enough to keep it out of trouble in a big empty field, hover and learn to control the menus while the
goggles are on your face.
Once you have done that, then start by doing some simple flights, again making sure that you are high enough that you can do banking turns and fly without worrying about hitting anything. As you get more comfortable, then you can move to more complex flights. Just remember that the way to get out of trouble is the same as when you are flying with the googles off.... take your hands off the sticks and think about what to do before moving forward again. There is always a drive to fly your way out of trouble but that's really the way to put your drone in a tree.
Litchi and Maven can be simpler as you can program Waypoints as well and just be a first person passenger while the drone follows a preprogramed route. DroneVR is designed to give you the full command experience and I find its best flown in sport mode so you can really get the feel of flight... but you need to start slow with any of the three apps.