Can a teleprompter be hidden during screen sharing?

Yes, on macOS, and only up to a point. macOS lets a window mark itself as excluded from capture. Apps that use the system screen-capture APIs honour that, and the window does not appear in what other people see.

What "best effort" means here, precisely

The exclusion is a request to the capture layer, not a guarantee about every possible recorder. It holds for apps that share the screen through the system APIs. It does not hold for a phone camera pointed at your monitor, and it cannot be promised for every third-party capture tool that may bypass the normal path.

So the honest instruction is: test it once with your own setup before you rely on it live. Share your screen to yourself in the app you actually use, and look.

On iPhone

Screen sharing from a phone is a different mechanism, and the same exclusion is not available. On a phone the practical answer is that the prompter is on the device you are reading from, not on the screen you are sharing.

How EyePrompt handles it

On Mac, EyePrompt's reading band is marked excluded from capture, and the app ships a Share Check that walks you through verifying it once with your own conferencing app. The claim is stated as best effort in the app, on this site, and in the App Store listing, because a privacy claim that quietly fails is worse than no claim.

EyePrompt on the App Store · What to look for in a teleprompter app