So I know that it’s possible to create scripts for use on spreadsheets using Google Apps Script, but is there support for using created scripts on documents? I know that the API provides services for creating and editing documents, though they bear the experimental tag, but I can’t seem to find a way to create and install a script on a document.
And when I say document services, I refer to the following link: https://developers.google.com/apps-script/service_document
You can’t find it because you cannot do it. Scripts can indeed manipulate documents using Document services (as you referred to) but the script itself should be linked to a spreadsheet or a Google site. Linked is probably not the best word since the apps script can be published to work as a standalone web application – in this case the link to the spreadsheet is used only during the development of your application.
I hope this makes things clear enough.