As I mentioned, the Courier.ttc font installed after macOS Big Sur is Courier by name only, and is known by Font Book as Courier New. That Courier.dfont that I "borrowed" from the older macOS Mojave is named Courier.dfont and Font Book knows it as just Courier.
If you have access to macOS Big Sur or older, you would be able to obtain the Courier.dfont as I did. On that older Mac, click on the Desktop to make Finder current. Press shift+cmd+G to open a Go To Folder window, and enter:
/System/Library/Fonts
When you press return, a new Finder window appears on that folder. Locate Courier.dfont and copy it to your Desktop. Close that Finder Window. Now, move that Courier.dfont onto a USB stick, properly eject that USB stick, and insert it into the Mac running macOS Monterey or later. Copy the Courier.dfont into your /Users/yourname/Library/Fonts folder. Now, you will have a font that appears as Courier in your Pages font menu.