Azure team open source products can almost all be used without Azure cloud.[1] I do use Azure but not for everything, you can definitely use Draft without Azure, it's Kube-native software so you can use it anywhere you have Kubernetes. (Like Tilt, from what I understand about it so far... Tilt and Draft look to be very similar tools, with different approaches.)
I helped someone on Twitter with this question last week. I have a (* single-node) Kube somewhere and I want to build images in it, and not have to pull them from a repository. The parlance in Kubernetes for this is, an imagePullPolicy of Never. (you actually do need a repository if you don't have a single-node Kubernetes, full-stop.)
Docker does actually run a VM with Linux in it, doesn't it? The modern version of Docker for MacOS also offers a Kubernetes checkbox, so if you're already using Docker, you needn't have another VM just for running Kubernetes.
This is certainly a problem that could use more clarity and for users, maybe a nice howto blog post for clarification, but it's absolutely possible to do this without a registry. I think Tilt mentioning "gcr.io" in the image tag is not necessarily a signal that you should actually push your image to the gcr.io registry. It's therefore possible to build and execute your containers while never pushing or pulling. If that's what you wanted to do, then that's exactly what you may do by setting your imagePullPolicy to Never.
(I have no idea how this works with Tilt, but I'd assume it's possible to use a similar approach since it's also on Kubernetes.)
The tweet in question: https://twitter.com/yebyen/status/1080534315157635072
[1]: the exception is things like aks-engine. You can only use aks-engine with Azure as I understand it, because Azure implements their own API for creating virtual machines, and nobody else implements that particular API. But I can't say how unique the Azure API actually is, or if it's also open source, could you build your own Azure in a rack, from all open-source components? That would be pretty cool, if you could...