edit "Recent Items" in Apple menu

How can I most effectively pressure Apple to change macOS so I am allowed to edit the Apple menu "Recent Items" item-by-item?

FWIW, there is no way to "pressure" Apple to do anything. You can send them feedback: Feedback - macOS - Apple

As mentioned, you can resort to manually edit the files yourself. I'm not aware of any third-party app to manipulate the lists.

The Recent Items lists can be Cleared. There is a menu item to do so in most apps.

The Recents Search folder is just that, the recently edited files. If you don't like the way that search folder works, create your own search folder and remove Recents from the Sidebar. File menu, New Smart Folder. Set the criteria to display the items you want to see. Likely the simplest search folder would be to tag the items you are working on with a descriptive tag. Make your search folder list files with those tags. When you change projects, you can edit the search folder to display only the new project.

You could also find a tool to remove the kMDItemLastUsedDate metadata from the files. I don't know of any to recommend.

Well, a possible workaround, get Text Wrangler or BBEdit & modify the file yourself, might require Finder restart...

/Users/YourUserName/Library/Application Support/com.apple.sharedfilelist/com.apple.LSSharedFileList.RecentDocuments.sfl

For Apps...

/Users/YourUserName/Library/Application Support/com.apple.sharedfilelist/com.apple.LSSharedFileList.ApplicationRecentDocuments