Downloaded but could not log in because I have cookies disabled on iPhone. Would be nice to have a cookieless login option (unclear if it is possible, API key?).
The cookie is merely needed by the web interface -- Ivory gets passed an API key. You can enable cookies temporarily, log in, and then clear them just fine.
How do other oauth logins work on your phone?
Fine. This one may be third party? Haven't debugged yet.
// Update: Works if allow cross site tracking and turn off hide from trackers. Re-enable after getting token.