QR text page, blocking storage and sharing

How do I prevent the demo page from being saved and shared?

How exactly should I understand this? If a page is not published, it can only be viewed locally in the preview. Only when the page is transferred to an FTP/sFTP server is it theoretically visible to the public. So simply do not transfer it to a server for testing. Did I understand your question correctly?

Or do you mean that you want to create a template and this should not be able to be saved or passed on?

“Or do you mean you want to create a model, and this shouldn’t be able to be saved or moved?”
Yes, exactly like that. The museum doesn’t have an intranet, so I’m publishing it to a web server. I’ve heard that a page opened with a QR code can be timed out. I haven’t found any examples of that.
On the other hand, these page contents are not secrets, but separated from their connection anyway.

You could define a time-limited URL in the .htaccess:

RewriteEngine On

# Valid until e.g. 10 July 2025, 12:00 noon (Unix timestamp: 1752148800)
RewriteCond %{TIME} >1752148800
RewriteRule ^musterseite/index\.html$ /expiry_info.html [R=302,L]

If the original URL is stored in the QR code and the expiry date is reached, the page “expiry_info.html” is displayed. Paths and Unix stamps must of course be adapted.

The timestamp could be defined here:
Unix Time Stamp - Epoch Converter