alt Hacker NewsMise installs itself as a static binary actually (but it's of course packaged in many registries), and while there are some third party registries it delegates to for some packages (aqua, asfd), most stuff I have installed is either built-in, or from PyPI, npm or GitHub, i.e. directly published by the upstream maintainers. More info: https://mise.jdx.dev/dev-tools/backends/
You'll see that mise recommends installing itself exclusively through package registries: https://mise.jdx.dev/installing-mise.html
pypi, npm, and even github (through releases) are registries.
curl | sh is an anti-pattern. It passes no security check.