Combination of zsh completions with fzf picker and gh copilot for CLIs.

I have a good setup here that you can learn from - https://github.com/fluxninja/dotfiles

Not a direct answer to your question but

> We have several exciting new CodeWhisperer for command line features coming in 2024 including support for Linux

Not explicitly what you're asking for but fish shell gets you a long way into what fig was offering for usability improvements, but without being a closed source SAAS cloud app laden with telemetry.

Many people suggesting zsh, but if you’re willing to move to fish you’ll get many features out of the box.

Zsh + powerlevel10k + zsh autocomplete