Can I check if a mobile is VR supported or not & Depending on that can i ask him to download app?

So we are developing an app where VR is one of the features of the app.
The VR scene is currently a separate app.
I know we can check if the phone contains gyroscope or not.

Now, if the phone is NOT VR SUPPORTED
We simply show a message that the phone is not supported

if the phone is VR SUPPORTED
Can we ask the user to download VR scene from either my server or from google play server? [Question 1]

Do we have to merge the VR scene in the main app? [Question 2]
Is there any other way to do this? or is there any guide for this? [Question 3]

Is the google VR SDK also works in IOS? [Question 4]