You can find a couple of simplified Inventor Add-In templates at this Autodesk University link:
MFG601910 | Bridging the Gap Between iLogic Automation and Inventor Add-Ins
In this class, I walk you through the setup and use of a simplified add-in template to get you up and running quickly with an add-in template that comes with some preconfigured tools that will allow you to quickly and easily create your own tools and buttons.
This class walks you how to spin up a basic add-in that comes with some simple buttons that you can configure to your liking.
And/or you can add to it and create you own.
Autodesk University 2023: Bridging the Gap Between iLogic Automation and Inventor Add-Ins, MFG601910