From Revolt Wiki

First showed up online on Reddit[1], limited information was available but appears that as of March, a repository[2] went live on their GitHub. The app is in very early stages of development and does not yet provide users an ability to sign up (without editing the database) nor talk with others.

They have limited activity on their Twitter[3], and boast quite a lot of future features on their website[4]:

Mikoto's Website

At some point they updated their website:

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Mikoto's Website

The main developer has also confirmed that the app will have a Discord API compatibility layer[5].