I found a paragraph in the documentation about using template files in a custom module. This way can be even used to override a template like I did here.
However, I am wondering if this is the correct way since I have read this answer (which seems does not work with dynamically-generated suggestion).
After some research I noticed that we can see sometimes the use of:
Apparently there is no clear documentation about that.
Is there a difference between adding a template and overriding a template, from a custom module? If so, what’s the correct way to add a template and the correct way to override a template?