Umutcan over the time since this extension was released there have been many requests for additional provider support. Including many different OAuth providers in the one package for convenience on the one hand is appealing, but at the same time could be considered bloat, as well as introducing additional complexity towards the maintenance of the extension.
As it stands, some of the most requested/popular auth providers are included directly in the extension. We've also made it possible improvements to allow additional providers to be added via seperate extensions to this extension.
For example these are just some of the extensions which add providers directly into fof/oauth:
There could well be more, but these are the ones I'm personally aware of. Of course, other OAuth extensions exist too, that provide OAuth with X login, but don't reuse the fof/oauth framework. I would suggest that those extensions that do not do this consider refactoring, as their complexity can be greatly reduced by using the framework provided already, as well as keeping a uniform implementation for all auth providers.
Creating an auth extension for Twitch and Steam using the fof/oauth framework is pretty straight forward. As you say, an implemention for Steam already exists, but outside of the framework. Twitch could be created perhaps with a couple of hours work (going on a cursory look at the Twitch requirements).
Telegram on the other hand is also possible, but would require a little more time spent on developing a solution for Flarum.
Perhaps your suggestions here could be separated out into the three providers and created under the Proposals tag, perhaps even with a bounty to encourage their development? 🤔
