The HomeKit-based integration is local control, but more limited.
The API-based integration requires their cloud service (and still doesn’t give full control).
Honestly, these are ok options if you have an Ecobee. If you want HA control (either local or through a cloud service), I’d recommend something else. The integrations are best if you are using to gather data or make other systems react, or if all you care about are simple home vs. away control.