A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Hi Dominique LOTITO,
I understand your great idea of allowing users to browse folder structures but not open the ultimate documents in there. If my understanding is correct, currently there has no out-of-box feature in SharePoint Online to achieve this kind of permissions level as the authorization will apply on the documents as well as subfolders.
However, I agree that it will be more user-friendly for organizations requiring this kind of function to let end users better understand the file structure. Given this situation, I sincerely recommend you use Feedback Community to suggest this feature limitation and add your valuable idea in the SharePoint · Feedback Community (microsoft.com) which is the best place to share ideas directly with the product building team and improve the Microsoft Products.
Meanwhile, I also sincerely recommend you give it a try to post in Microsoft Q&A Community, which is the specific channel to handle some developed demand with customized SharePoint environment design. You may use sharepoint-dev tag and office-sharepoint-online tag when " Ask a question". The engineers in related team will focus on your specific scenario and provide possible workarounds with customized building methods.
I appreciate your time and effort on checking these above and thank you for your time and cooperation.
I hope that you are keeping safe and well.
Best Regards,
Mia