I’m new to HA so still learning the terms.
I’d like to develop a new capability and be able to package it so that once installed, it provides out of the box functionality, without anyone needing to customize yaml files.
My functionality is basically a custom sensor (that relies on the built-in REST API calls) as well as introduce a card type for it (can re-use the existing gauge type).
What should I look for to learn to package this up?
I understand that add-ons are more about external capabilities that sit along HA. So I guess what I’m looking for is one of those custom_components or an integration ?
Would appreciate some directions to read/watch to make this work 
Thanks!