If you're looking for way to get userdebug functionality without building a huge source tree, I created regraph[0]. It's similar to other solutions but does not inject sudo or root, other than the supported adb root path.
It starts with an upstream GrapheneOS build and modify the system image (super) in place, signed with the published userdebug keys.
It starts with an upstream GrapheneOS build and modify the system image (super) in place, signed with the published userdebug keys.
[0]https://github.com/tmzt/regraph