Google's Artifact Registry can be used as a Maven repository (see https://cloud.google.com/artifact-registry/docs/java/quickstart) but deps.edn cannot currently refer to this as it does not provide hooks for custom wagons/transports.
In tools.deps, there are a couple ways this could be done. First, there is an existing Maven wagon for accessing artifact registry, so adding that + the wagon transporter (we use the newer transporter framework) + registration would allow custom urls to work with the existing code.
Or, another option would be to write a custom deps procurer that talks directly to Artifact Registry, not sure of the effort there but can't possibly be too much. Probably some subset of what the code at https://github.com/GoogleCloudPlatform/artifact-registry-maven-tools is doing. Probably the hardest part is figuring out the transfer of credentials. One of the benefits of this would probably be a smaller set of external deps.
And finally, clj would need a way to provide custom procurer support, which we have not yet designed.
