I think it's important that rules_codeowners allows defining global owners at the project root, separate from a codeowners() rule. Based on the pattern by many other rule sets, this should be done with something like the following:

# WORKSPACE

http_archive(
    name = "rules_codeowners"
    ...
)

load("@rules_codeowners//:foo.bzl", "codeowners_register")

codeowners_register(
    global_owners = [
        "@teamA",
        "@teamB",
    ]
)

This allows defining global owners in the global scope (e.g. at the root of the workspace), but keeps it out of any codeowners() rules for cleaner organization.

Sourced from: #13 (comment)