I doubt this is possible given how locked down Nest is, but I’ll give it a shot.
Is it possible to override the temperature that the Nest sees? My apartment was brilliantly designed such that the thermostat sits between a vent and an intake. So it always sees the temperature change too quickly and undercompensates for other rooms.
Ideally, I would like to be able to combine several NodeMCU-based temperature sensors to create some sort of weighted average, and then override the Nest’s detected temperature with this new, more accurate measurement.
I’ve worked on similar projects as an engineer, but my budget is pretty tight when it comes to home projects.
A thermostat is basically just a temp probe and some relays. If you want to create a sensor array and feed that back to something to control the heating/cooling the generic thermostat component would work.
Three relays will work for a lot of setups. One for heat, one for cooling and one for the fan.
If you want to keep the nest you could use HA to control the nest. Basically create a sensor to average your temp reading and act based on that sensor.
Here is an example for heat.
Grouped temp sensor drops below the desired level
Automation is triggered by this drop in temp and turn the nest mode to heat and the temp to 85 degrees (setting it high will ensure the nest stays on even if the nest temp sensor goes above the average temp sensor in HA)
Once the average temp sensor reads the desired temperature an automation triggers to set the nest mode to off.
A bit crude but the only thing I can come up with right now. When you are away from the apartment I would put the nest back in control just to be safe.