Heck, mise has an HTTP backend that can install binaries from any URL. I use this to manage Atlassian CLI, whose official Windows binary is not on winget.
Agreed, this looks like a far more limited mise alternative that still requires a completely different tool to run.
Not sure if I'm misunderstanding the private binaries concept - what advantage does gzipping and encrypting the binary and putting it in an unlisted gist have over just storing a release in a private git repo only I can access with my PAT or key? Seems needlessly complicated.