lberrymage greenmonster There isn't exactly, but most changes aren't device specific, and those that are are called out in the release notes. However, there are device-specific repos for SELinux policies, device sources, and kernel sources you can look at such as https://github.com/GrapheneOS/device_google_barbet-sepolicy and https://github.com/GrapheneOS/device_google_barbet. It would be better to look to the release notes for changes though.
[deleted] lberrymage I strongly suspect their idea behind this is to audit the code on each new update so they can verify all the changes are "safe". Could be wrong though.