Is there any immutable distro that's based on Hyprland? I really like their approach to tiling, but at the same time I prefer to have a solid experience without worrying that the next update might break some dependencies.
No distro is really based on a window manager or desktop environment. Some provide defaults and premade configs. I kind of doubt any include hyprland as an option at installation, but, Wayland compatibility notwithstanding, there's nothing stopping you from throwing hyprland on whatever you would like. The best approach is to take a Wayland-ready setup, like Leaflet suggests, and just install hyprland.
Ublue provides a really solid base template that makes it very easy to do stuff like this, all the heavy lifting of a distro is done by fedora, ublue adds the codecs and drivers and build system for updates.
Wouldn’t be unreasonable to make your own distro with it honestly.