At the moment I can move the .desktop file to the android device and (using FX File Explorer) open as application, choose Firefox, allow Firefox to access files and then it works. But whilst giving a file manager access to my files is a necessity, I don't really want Firefox to have access to my files (which it presumably needs by this method in order to 'read' the .desktop file). I really want the file explorer app to 'read' the .desktop file (as it already has access rights) and then forward the url it found there to my browser.
This is exactly the way both my cloud storage apps (Dropbox and Nextcloud) work when they encounter .desktop files. They just open the url in a browser without needing the browser itself to access the file.
Is there a way to make this happen within a file explorer app?