Status of completions for shells other than bash (e.g. zsh, fish)?

Snap currently supports bash completions, and the documentation states:

…in the future that same mechanism may be enabled in other shells as well.

What is the status of completions for other shells? Is this likely to be something we can expect in the short- to medium-term future?

I searched for zsh completion and search for fish completion on this forum but did not find any existing status.

I also searched for zsh and searched for fish on but did not find anything relevant.

Downstream user request:

Many thanks for any information!

For zsh at least using a plugin such as will handle it, doing the same in Fish is just matter of exercise.

Completion support for zsh is part of the snapd package since 2.46.