My `~/.oh-my-zsh/custom/themes/lambda.zsh-theme` file, which is a custom oh-my-zsh theme based on lambda.

lambda.zsh-theme

function precmd_get_conda_env_name() {
  if [[ -n $CONDA_PREFIX ]]; then
    if [[ $(basename $CONDA_PREFIX) == "mambaforge" ]]; then
        CONDA_ENV="base"
    else
        CONDA_ENV="$(basename $CONDA_PREFIX)"
    fi
  else
    CONDA_ENV=""
  fi

  echo $CONDA_ENV
}

PROMPT='%{$fg[blue]%}%n@%m%{$reset_color%} %(?:%{$fg_bold[green]%}➜:%{$fg_bold[red]%}➜)%{$reset_color%} ($(precmd_get_conda_env_name)) λ %~/ $(git_prompt_info)%{$reset_color%}'

ZSH_THEME_GIT_PROMPT_PREFIX="%{$fg[green]%}"
ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%} "

Usage:

1. Install zsh and oh-my-zsh
2. Set zsh theme to lambda in ~/.zshrc
3. Put the custom lambda theme file into ~/.oh-my-zsh/custom/themes/
4. Disable the default conda prompt modifier: conda config --set changeps1 false