I think it is not possible. But maybe four options. Green users are allowed users, red users are other users e.g. only you.
1.) use a markdown file instead of top folder
Share the green folders (but not the top folder) and green files normally to the green users. Instead of share a top folder create a markdown text file (.md) with links the shares to the green and red folders and files. Write that the red folders and red links does not really work for green users.
2.) App Link editor
Maybe you can install the app Link editor (actually not Nextcloud 27). Then you can create in the top folder only a link to another shared (red) folder outside of the top folder. Do not share the red folder itself with the green users.
3.) Devide green and red
Move all red folders and red files to another structure outside from top green folder. Use different shares for red and green users at any time.
4.) Use encrypted zip files
You can upload the files/folders in single encrypted ZIP-files with an easy password. Only you can access the files. I like 7-Zip.