This Token Store is conceptually different. It may be accessed both with Management API Client permissions, or with signed-in user account permissions. These tokens are private to the user account. Unlike Management API Client private tokens, these tokens may be shared between applications and services. To do that, ACLs must be defined. Se here for more information.
https://oneportal.t5.fi/apidoc lists the API end-points under /user/{userID}/token.