I’ve been using nushell as my shell for a long while. Completions are not as polished as zsh - both the published completions for each program, and the UX for accepting completions. But you get some nice things in exchange.

I LOVE using nushell for scripting! CLI option parsing and autocompletions are nicely built into the function syntax. You don’t have to use the shell for this: you can write standalone scripts, and I do that sometimes. But if you don’t use it as your shell you don’t get the automatic completions.

Circling back to my first point, writing your own completions is very easy if you don’t like the options that are out there. You write a function with the same name as the program you want completions for, use the built-in completions feature, and it’s done.