Improving zsh autocompletion?

Hi. So I've been a fish user for a while, but I've always gotten frustrated with it not being POSIX compliant. I tried to use zsh with oh-my-zsh to still benefit from fish's capabilities on zsh, but I had 2 problems with it: it was incredibly slow, and it wasn't as good. As I recently found out, the plugins can just be sourced in zsh directly, skipping oh-my-zsh, and fixing my speed issues. But the second issue remained: zsh-autosuggestions is just not as good as fish's autocompletion feature, which suggests commands in a user's PATH, as well as autocompletes directories, without me having ever accessed them, meaning they weren't even in the history at that point, which allowed me to hit the ground running. I want that with zsh as well. Is there a plugin or something like that, which allows for these extra features, and can autosuggest commands from PATH and autocomplete directories? I really want to switch to a POSIX shell, but the lack of this feature would make it feel like quite a downgrade. Thanks.