Old thread but thought I'd reply as it took me ages to work out the answer and this is high up Google's search ranking. Hope this helps someone!
I also want to use Nest because the app / controls are so much better than awful ones from specialist UFH companies.
Engineered wood requires temperature to be kept below 27 degrees at the floor.
The Nest sensors can't connect to a floor probe.
That means you risk running more than 27 degrees on the floor, and the engineered wood delaminating.
The best workaround (I've found) is to use SONOFF temperature sensors. These can be connected to an Amazon Echo 4 (or any Echo with zigbee) and then Alexa can run a routine that switches off the Google Nest heating in the zone / room if the temperature reaches 27 degrees on the SONOFF sensor.
Essentially, the NEST control is the thing you use day to day, and the SONOFF/Alexa system is running in the background as a failsafe.
Important things to note:
You have to connect the SONOFF sensors directly to the Echo, not to a ewelink bridge. This is because the Alexa skill for ewelink (the sonoff app) doesn't allow temperature sensors to trigger routines; you need the Echo to trigger the routines itself.
You can use as many sensors as you like with one Echo.
You can't use Google Home for this. This is because Google Home doesn't allow many things to trigger routines: Alexa is much more flexible.
You can't use IFTT for this. Google Home won't accept triggers from IFTT or allow IFTT to control Nest heating.
CONs: This setup switches the heating off when the floor temperature reaches 27 degrees. It's basically a failsafe. The heating won't automatically come on again - so it protects your floors but is less effective than a floor probe at regulating the heat. (In theory you shouldn't need floors at 27 degrees to heat the room, but...) If you need the floor temperature to hover near 27 degrees then this won't work for you.
PROs: You can move the sensors to any hotspots in the room (e.g. where pipes are bunched or a sofa is providing more insulation). So you have more flexibility than a floor probe.
Using Alexa feels like a weird workaround, but that seems to be how it is right now. Maybe this will change with Matter being introduced.