Previously I set my Chromebook to run Godot but I didn't like opening terminal to run it and would rather have a pinned icon to launch Godot. Debian Packages installed from Chrome's Files have such shortcuts created automatically but AppImages don't. To make a launcher for an AppImage, it's necessary to make a .desktop file and place it in a specific folder.
One way to make a .desktop file is to open the Text app and write the descriptions by hand.
[Desktop Entry] Name=Godot Comment=Great Game Engine Exec=/home/goldenxp/apps/godot33 Icon=/home/goldenxp/icons/godot-icon.png Type=Application Categories=Development;Graphics;Game
There are other options one can take advantage of like keywords and terminal display, etc.
When you're satisfied, you need to save the file in a specific location so that it's picked up by the Chrome OS Launcher. Read here for some info on this. The location I'm going to use is
~/.local/share/applications/. It's hidden by default so when you want to save it, you'll need to show hidden files.
Once you save it, it should take a couple of seconds for it to show up in the Launcher. Now you can click to launch and even pin the app to the shelf.
Note: I've noticed that some .desktop edits don't register updates in Chrome. The workaround is to delete the .desktop file and remake it.