File Manager with Additional Functionality -- 2

I'm looking to build a larger web application to manage a medical practice. I'm collecting proposals about this project as well via another job listing. Part of this application will be the ability to handle PDF files via a file manager. Those who are reviewing the larger project above state that the integration and development of this file manager may be problematic in that the functions I need are based upon desktop software as shown in the videos I'll provide. Essentially, the software needs to display PDF files in thumbnail view and sort via the usual methods (size, name, date, etc) and then allow drag and drop stack (combine) and unstack (uncombine into separate files). Many have said this is not possible with web software as if the files are stored in the cloud (One Drive, Dropbox, G-drive, etc) there exists no API to allow this. I understand this point but such manipulations can be performed upon local files. I understand there could be a hybrid solution. One attraction I had to Node is that it installs exe files on the users local machine and thus can perform manipulations on that machine, almost like desktop software. (I think there's also a platform called Electron that allows this). So the user would manipulate those local files on their machine as I have One Drive or Dropbox running in the background and they are automatically backed up to the cloud and synchronized across all user machines. I use about 4 computers and have 1 other user so all PDF files are backed up across 5 machines (which is also a good backup plan). It only works, however, because I have so few users. Right now there is no file conflicts (i.e. - 2 users trying to access the same file). With more users this could be a problem. Ideally it would be better if the files that were accessed in the cloud were accessed directly. This way, multiple users could use the product and not worry about file conflicts. But I'm far away from having multiple users and I don't really think that will happen. The file manager has some unique functionality but I've been sent some links that show a Node file manger that could be modified to perform as I want (stacking and unstacking) as shown in the videos. Here's the Node stuff I found for the file manager: There is a Node module called FS, which can be used to read from file, append data to file, this URL link has some documentation :- [login to view URL] There is a npm to merge pdf files :- [login to view URL] And here are links to other Node file managers: [login to view URL] (this one is quite fast) [login to view URL] [login to view URL] [login to view URL] Some have suggested using C++ and trying Web Assembly to build essentially a desktop app and having it run in the browser. I don't know if this is feasible. I will also attach a screenshot of the desktop/dashboard of the larger application. See the attached document which details the entire project. Go to page 10 and section "C" which details the file manager. I'll also attach videos showing how the file manager should function. If anyone is interested in the larger project then feel free to comment. I will only proceed on this project via a milestone approach where time and cost estimates are known from the beginning. I will give strong preference to those freelancers here designated as "preferred". Thanks for your interest.