I think you'd like what I've done with mise. You can have tasks in your global config (~/.config/mise/config.toml) which by default are shown no matter where you are. `mise run` will show a selector by default of all tasks available, so no need to manually setup fzf. Shebangs work the same. Commonly, mise users would also put "uv" into their config so other users don't need to set that up separately from mise itself.

Interactive inputs are something I'm planning on shipping relatively soon. It would not be hard to do—I've got the ui components to do it and the data model supports it.