Unfortunately, most VR headsets are made for specific phones/devices.
Since the lenses combat the size of your device you don't want to use a screen that takes up more space than the headset has room to hold. That means you don't want to use something larger than a phone for portable VR.
On that note, I can't imagine having a tablet in your head to be the most comfortable thing to use.
Instead, try checking out the Oculus Go if you're looking for a portable headset. It doesn't require a phone to play it, completely cordless and standalone.