I'm interested in adding OCI (docker) registries as package/index sources for cargo.
OCI registries can store far more than just Docker images - it's how devcontainer features are distributed, and at least some other languages are using them for library or binary distribution mechanisms.
This may be more attractive to some parties for internal package hosting (since just about every cloud platform has OCI registries), and makes using private packages on GitHub more attractive (since using private Git package sources is cumbersome).