It's a bummer docker still doesn't have an API to explore image layers. I guess their plans to eventually transition to containerd image store as the default. Once we have containerd image store both locally and remotely we will finally be able to do what you've done without the registry wrapper.
You're bang on, but you can do things with dive (https://github.com/wagoodman/dive) and use chunks of the code in other projects... That's what I've been doing. The license is MIT so it's permissive.
But yes, an API would be ideal. I've wasted far too much time on this.
It's a bummer docker still doesn't have an API to explore image layers. I guess their plans to eventually transition to containerd image store as the default. Once we have containerd image store both locally and remotely we will finally be able to do what you've done without the registry wrapper.