Instead of going without HW, I'd rather build a SeedSigner from off-the-shelf components (can be ordered or bought in store) and remove the antenna.

Well, the whole project is open-source, and it should be relatively easy to modify the code in a way that larger screens just have black bars on either side. I could have a crack at it if you really can't find something in Zero form-factor with the right pixel count. It would likely be a little back-and-forth in DM since I don't have the hardware on hand.