Is it possible to create a shopify app that loads a script tag on the store after it has been installed? I have a small functionality in a javascript file but I don't want my clients to add the script manually. They would just install the app from the shopify store and have the script automatically added.
creating a script tag is just an api call so a proper Shopify app can do that but so can an external app where you get your customer to generate and give you a private app key/password pair.
Installing an app is easier for the customer but creating that app and shepherding it through the app store acceptance process is a fair bit of work for you.