I've had three different galaxy fold zs and each one has had a broken interior screen. My current fold has a broken internal screen and I'm on vacation.

The inner screen is definitely not as durable as the outer one. I've not tried it, but it does feel like a hard press with a fingernail will leave a mark.

My dad is in construction and has gone through at least 4 flips that I know of in the time that I've had my S25, probably more.

By durable I guess I mean they don't destroy themselves just by existing.