This page describes a personal, single-user software integration. The “Home Assistant” application is a private Google Cloud project owned and operated by one individual for his own use.
It connects his own Home Assistant instance (home-automation software running on his own hardware) to his own Google Tasks account, so that his task lists can be shown on a dashboard in his home and tasks he checks off there are marked complete in Google Tasks.
It is not a public product or service. It is not offered to any other user, and no one else can sign up for it or use it.