#mastodon, #fediverse, #new - Is there a way to use an alternate mastodon UI for your instance, automating the oauth flow?

For example, if I wanted to write a UI for our internal organization's instance, but not require them to go directly to the instance to signup, is that easy enough?

As an example, client UIs like Hyperspace (and others) could perhaps have better adoption, for a college club for example, but it would be difficult to make the signup flow look like the Hyperspace UI.