Third party fish eye lenses and headsets

I’m wondering if we are limited to only using the supplied FEL and headset?
I, and I’m sure others will, own other GCardboard headsets (Homido, BoboVR etc) but the lens supplied doesn’t allow the phone to fit. The reason being for IPD and focus adjustments and audio controls.
I’ve seen lenses online which a more flush with the casing when attached which would allow them to fit into most headsets.
Could be a good thing to create a list maybe. Have the board contribute?