I think the Nest Secure products used a protocol called Weave on top of Thread. Weave was an application layer protocol like Matter and was open sourced by Google, but I don’t think any other projects picked it up and integrated with it. There is no Home Assistant support as far as I can tell.

It’s a shame as the Detect sensors are cute little devices.

Homebridge might be worth a shot. I know its Nest integration is better in some ways than HA's native integration.