Overview page: https://www.gog.com/en/anniversary
Direct sign up for Galaxy Linux beta: https://www.smartsurvey.co.uk/t/YEF5EV/
I don't fully understand the why. No GOG sells games without DRM, that's it's whole selling point. Why have a launcher (other than maybe for installing)?
Anyway. Speaking of GOG I'm more excited for Physical games
Although I don't think I would actually utilize it.