I find myself having to manually create a lot of .desktop files in order to get shortcuts to third party applications or scripts I wrote.
On Windows I used to be able to right-click any .exe file I want and create a shortcut from it with one click.
So what I'm looking for are Linux tools that make the process of creating .desktop files easier. (For example a context-menu integration or a dedicated GUI where I can easily select my target executable and have the other settings be generated automatically.)
I'm usually using Gnome or KDE in case that matters.
Unless I am misinterpreting your question, it is seen that every linux desktop environment has a gui to create a launcher for 3rd party software and all other apps. The link below shows gui and commandline launcher information for many de. In addition to the below I use mate and that also allows 3rd party desktop launchers. Generally a right click on the desktop can be used to start the process.
Start the gui and input the properties. The properties are input manually but are quite minimal. Sometimes the "command" to actually start the app can get tricky but a little trial and error has always solved the problem. There is then a template command for other similar apps.
Save gui and then activate from the desktop. The guis create .desktop files in the Desktop directory.