Having a default tag taxonomy with tags displayed on each page and pointing to the corresponding tag index.
Extensive explanation of the tag support idea: intuit/Ignite#126 (tags display on pages, tags index, tags list, etc.)
Examples
Examples in other staticgen:
Screenshot on retype:
Tags button embedded on a page: 
A tag index (https://retype.com/tags/config/): 
The index of all tags (https://retype.com/tags/): 
Examples on my Hexo blog:
Tags on an article: 
A tag index (https://blog.raw.pm/tags/eop/): 
The list of all tags (https://blog.raw.pm/tags/): 
A tag cloud widget: 
Having a default tag taxonomy with tags displayed on each page and pointing to the corresponding tag index.
Extensive explanation of the tag support idea: intuit/Ignite#126 (tags display on pages, tags index, tags list, etc.)
Examples
Examples in other staticgen:
Screenshot on retype:
Tags button embedded on a page:
A tag index (https://retype.com/tags/config/):
The index of all tags (https://retype.com/tags/):
Examples on my Hexo blog:
Tags on an article:
A tag index (https://blog.raw.pm/tags/eop/):
The list of all tags (https://blog.raw.pm/tags/):
A tag cloud widget: