Artifact registry has beta support for Maven repositories. However,
best practice with Maven is to use a "repository manager", which is essentially a proxy+cache that lives between the public repos and you.
There are lots of free and open-source options for repository managers, and it can even be done
with nginx. It's not hard to set up and maintain the repo manager yourself, but it would be really nice if artifact registry could take care of it for you.
Is "repo manager" functionality on the roadmap for artifact registry?