I don't think taking photo through glass will have any issues. The lens is also going through glass now..
The bigger question is whether do we even need it.
I know iPhone used to state that their glass is sapphire crystal. So unless you're really careless, it likely won't scratch/break. In this case, then a TP will not be necessary.. And my s7e is likely sapphire crystal as well (I recalled reading something few years back but not sure if my memory failed me), and I don't hv any scratches after using for 2.5 years (camera glass only)
But if HW is using gorilla glass etc, I think we may need it, as it will scratch quite easily..