I'm really excited about this: building a scalable Access Control is a foundational challenge of cloud-scale systems, and I'm happy to see a new contender.
Is this like an "Open-Source Core" model, where the basic core platform is open-source but all the extra features to make it usable (to put it bluntly) in a given org are what you're selling?
(in my org it takes ~2s to lookup group membership (& thus permission) of a user on a cache miss, which is just shocking. I'd love it if we migrated to SpiceDB, but of course at our scale that won't happen anytime soon)