I'm actually collecting playbooks and here's my list (apart from hanno):

• https://thoughtbot.com/playbook
• https://handbook.bakkenbaeck.com
• https://github.com/basecamp/handbook
• https://medium.com/jackrabbit-mobile-publication/playbook-65a0d42ef9cf
• https://productcoalition.com/the-typeform-product-playbook-49e1a5cc3a08

As for hanno, I loved their case studies, which are now removed since they focused on healthcare. But they also got this: https://github.com/wearehanno/designthinking/wiki

I recently had a client referenced playbook.cio.gov. For some reason it got me thinking and I went down a rabbit hole and found this site.

I like of like the idea to onboard new designers, unity processes, or just educate sales/clients on this mythical buzzword "UX".