Hey there, we haven't spent much time on the Ruby ecosystem, unfortunately. We have some Ruby bindings, but they haven't been regenerated for v1 just yet. If you're interested in using them, we could get them working for you. I think calling out to authzed from a cancancan policy makes sense, but I'm not a rails dev.
For consistency, right now, we simply don't commit our db transactions until we've written relationships into authzed. It isn't perfect, but we're exploring other alternatives in the future, like remote transaction APIs.