The big advantage for me is that lact runs as a (systemd) daemon. This is more convenient for me than having to autostart CoreCtrl.

A disadvantage of the daemon is that it can’t be packaged on flathub.

Enable and start the service (otherwise you won’t be able to change any settings):
sudo systemctl enable --now lactd
You can now use the GUI to change settings and view information.

LACT has an API over an unix socket.

https://github.com/ilya-zlobintsev/LACT/blob/master/API.md