The fee you add for DoorDash etc should not be considered a tip. Tips are given after service is rendered, and are based on the quality of service. These fees are more like a bounty. “I’ll pay $10 to the person that brings me a hamburger, dead or alive.”
There is no install needed, you can just edit permissions and make the file executable and then when you open it or click it the app runs.
What won’t be created by default is an application menu to run it from whatever desktop environment you use. You can create those if you wish. You can create a launcher in the menu manually, or you can use a tool called AppImageLauncher to create these for you.
There’s a pretty good explanation here: https://askubuntu.com/questions/1311600/add-an-appimage-application-to-the-top-menu-bar