You can embed a PDF file into a cell of an Excel worksheet and then use Excel's security features to lock the object. This allows you to take advantage of both technologies.

IDG. macOS used to show an overlaid lock icon as at left in Mojave; in Big Sur, at right, it no longer provides this indicator in the Finder. Prior to Big Sur, locked files would have a lock image ...

In order to lock your Mac, you'll need to first set up a password. This password will be required for both logging into your Mac as well as approving changes to your computer. 1.