Using twitter app as an Amazon IAM OpenID Connect Identity Provider
These are the settings I have behind my twitter App,
And these are the settings I've tried in Amazon IAM,
Which I'm assuming doesn't work because twitter is providing oauth login only, not full OpenID Connect compatible options. Is there any way I can get twitter as one of the login options, or build some sort of middle server, or similar, to be able to make this work?
You are correct, this is because Twitter only supports OAuth 2.0 delegated access to the Twitter APIs for 3rd party clients. Twitter does not support an OAuth 2.0 based signin mechanism (like OpenID Connect), their current signin mechanism is based on OAuth 1.0, see: https://dev.twitter.com/web/sign-in/implementing and https://dev.twitter.com/rest/reference/get/account/verify_credentials
You could indeed build a middle server to bridge standard OpenID Connect to Twitter's OAuth 1.0 signin mechanism. I am not aware of the existence of such a bridge as an open source product. There are commercial products that can do this.