It looks like the source still has some TODOs, so just wanted to see what the status was or if there was a workaround.
/Users/timfee/.local/share/fig/plugins/ohmyzsh/custom/plugins:
drwxr-xr-x@ 8 timfee staff 256B Feb 24 15:57 pnpm
drwxr-xr-x@ 26 timfee staff 832B Feb 24 15:57 zsh-autosuggestions
drwxr-xr-x@ 7 timfee staff 224B Feb 24 15:57 zsh-history-substring-search
drwxr-xr-x@ 22 timfee staff 704B Feb 24 15:57 zsh-syntax-highlighting