I’m not sure if you want to use your Nest with some eTRVs in your rooms or not… This is often the case in Europe when they have hot water valves in each room…
if you choose my NextBundle, you can create your own rooms/zones/schedules using my zoned heating/cooling smartapp called ScheduleTstatZones.
For each room, you can associate your eTRV (if any) or any room thermostat that controls portable heaters/coolers/splits/fireplace/baseboard heaters, etc. and schedule the right zones (composed of 1 to many rooms) during the day.
For instance, at night, you may want to only heat/cool your upstairs bedrooms; the rest of the eTRVs would be turned off or set to a lower setting. During the day, it may be the opposite (ground floor zone only where your kitchen/dining/living rooms are located).
You can even set some delta temps (+/-) in each zone based on the main thermostat’s setpoints (Nest in this case) to make some rooms cooler or hotter. So, you can program some “boost” during the day using your own zones/schedules…
For more details and all use cases available, refer to the ST community wiki:
P.S. I have several contributors in Europe with this kind of setup, and it works very well.