[rbanffy]

I would love if the screen could take up more space, even at the expense of a little extra thickness.

[jansan]

I think that there could be a wider screen if such formats are available. Once we have betavoltaic batteries, the entire card can be screen.

[rbanffy]

I'm not sure beta voltaics will ever reach LiPo densities. All materials I know would be unwise to place in your wallet, or anywhere near your body.

If we are OK with a battery and a beta voltaic source, a tritium one is reasonably safe and can trickle charge the battery when the device is in deep low power mode. The battery can still be charged by the induction coil.

[WithinReason]

That actually exists, with even the same CPU but no NFC: https://www.xteink.com/products/xteink-x4

[rendaw]

That looks like it's the size of a smartphone. It's 7 times thicker... I'm not sure that qualifies as a little thicker, plus all the other dimensions.