Hello everyone,
We are sorry that Emerald Blue didn't have controller support day 1 of release, and we are and have been working on it. We are making progress, but were making sure everything works before we post a update.
Linux support: At the moment, there has been some challenges regarding native Linux support but we are going to get that posted up for any Linux/SteamOS users. As of this moment, we'd recommend using Proton until we have a working Linux build, and it will be posted as soon as it is ready.