We've thought about adding a screen to a future product, but it begs the question of how much information you want displayed in order to make your authentication decision.
And even if a screen gives you more information, are you authenticating an action where the cryptography terminates in the device? If you are authenticating an SSH session for instance, the screen helps you ensure you are authenticating a login to the right server. Once you have authenticated though, nothing prevents the attacker in your local machine from using the established SSH connection.
Reading through an entire email (maybe MIME multipart encoded) on a small OLED screen isn't fun; on the other hand, something like "confirm transfer of €x to IBAN y from your account z" would be great – but needs support of your bank.
That support is incredibly hard to get. Android has supported "protected confirmation" [1] for many years now (on Pixel devices), but I have yet to see support for it by any real-world service I'm using, and I'm not holding my breath, since I can't even use FIDO with any of my banks...
[1] https://developer.android.com/privacy-and-security/security-...
A screen and 2-3 buttons would be nice, though; also a tamper-evident/tamper-responding package. But my main desired use case for this is a lightweight app-specific HSM so I'd just need to validate integrity of device before connecting it to host. USB Armory II is the main alternative.