[LeEco Le Max 2 Accessories] abufrejoval:
Cardboard just works out of the box

Well the Google Cardboard project is just bits of cardboard, two fresnel lenses and evidently some kind of "hammer", which translates an external button into a touch on the screen, the only physical interaction supported by cardboard (I use the blutooth mouse for that: I bought and tried the new Microsoft Xbox controller, which supports Blutooth, but none of the Cardboard games seem Controller enabled: Pity!)

So all I did was just to install and launch cardboard applications from the Google Play store: They can't verify if you actually have cardboard "hardware" or some other kind of lenses.

Now, I'm using Cyanogenmod which doesn't contain the VR stub application which the Indian and Chinese ROMs seem to contain. And perhaps that stub application is causing trouble in your case, because it launches whenever you connect the device.

If you don't want to switch to CM, you can simply remove the app from the phone if it's rooted and you have some kind of app-remover or Titanium Backup. Then it won't launch the stub (which evidently isn't useful outside China or without a LeEco app store) and you can use the Cardboard apps without interference. Perhaps you can also just switch away from it, I haven't really tried extensively because my son wanted his phone and I'm not going to try on my "production" phone (swapping a production ROM forth and back with full backups simply takes a while).

Phyiscally and logically LeVR Pro1 seems largely a copy of Samsung Gear VR, even if it's not a downright clone. As far as I can tell its touchpad and back-button duplicate the same thing on Samsung. But without a proper driver it's dead and with a CM ROM at least there is absolutely no reaction if you insert the phone into the headset nor will the external USB-C connector have any use, which is a real pity.

There is a good chance that won't ever change, unless LeEco were to publish driver sources for the LeVR Pro1, which I sincerely doubt. I've also tried installing the VR Setup application on top of the CM ROM (I won't run no EUI ROM for "production"), but it just crashes. Evidently it is deeply intertwined with the Chinese LeEcosystem, for which I have absolutely no interest (while LeEco has absolutely no interest in supporting users which are outside it: I believe they sell their phones below manufacturing price).

While LeEco is trying to enter the North American market, it seems to draw its baseline at the LeEco Max Pro3, which doesn't have the 2560x1440 screen (and is more expensive). They may be launching another VR headset soon, potentially with another phone which is DayDream compliant.

LeEco doesn't seem to believe in backward compatibility or long term support.

Well nor does anyone else, evidently, they only charge for it and that at least LeEco did not.

Essentially we have a super cool Cardboard and I'm happy enough with that, since I have two Oculus Rifts (DK2 and CV1) to ease the pain (actually I also have a DK1 but that's a museum piece now). It allows me to watch movies on a virtual big screen and some of the Cardboard apps are great to impress friends.

Unfortunately there is little chance it Le Max2 or LeVR Pro1 will be good enough for the new Google Day Dream base requirements, so it's basically obsolete already. Should LeEco, CM or some XDA-Developer make it Day Dram compatible anyway (without certification), I'd be happy, but I don't know if Google Day Dream will be such a great success. The fact that essentially all of today's smartphone population is already disqualified may not sit too well with potential VR enthusiasts. And at €1000 for a smart phone which isn't really any faster than the €230 LeEco Le Max 2 in base configuration, a Google Pixel XL may simply be too much of an entry price for Android VR.

Google is doing its best to kill Android while they are grasping to replace the Internet and free choice.