Hey there - I am tooooootally foreign to the smart home world. No idea if this is easy, difficult or what.
I have some fans that I’d like to run when my HVAC kicks on. Is there a way I can set up three smart plugs to activate when Nest turns on heat or AC? Which plugs? What software?
Thanks for your help 
Do you have a smart home ecosystem in place using the Nest or just getting started?
(i.e. is your Nest part of Apple HomeKit, Google Home, Amazon Alexa, Samsung SmartThings, Home Assistant, or another hub/automation platform?)
A smart plug on its own cannot do what you want. You need to link your Nest and SmartPlug through a home automation server that can process a rule such as “When Nest turns Heat on, turn smartplug XYZ on or off”.)
As stated, this is a straightforward desire, but unfortunately if this is your first foray into any kind of smart home / home automation, you’ve stumbled into an automation that isn’t available easily off-the-shelf so requires careful planning and understanding of what each system can do and whether the chosen (or prospect system) has the ability to receive status triggers from the Nest (or other) thermostat.
Others may chime in, but I’m almost thinking maybe you should take an indirect route and get a connected temperature sensor and create the smart plug rules based on the room temp and then turn on or off the fans.
Not ideal and might be more finicky, but the automation side of it is much easier as there are temperature sensors for every automation system that let you build rules based on the room temperature values.
The Nest is a finicky device to integrate into systems, it might turn out simpler to replace the Nest, if possible, with another brand of smart thermostat that is directly controllable from the system you want to use. (I know ‘tear it out and use something else’ is never the ideal answer, but sometimes it is the least time consuming and actually least expensive solution?)
Thanks for the super detailed response.
No ecosystem in place. I have a few Nest devices (thermostat, doorbell, and whatever they call their smoke detector). They were cool years ago when I got them, but I’m really unimpressed and I’ve been fantasizing about Ecobee in particular. Seems to be the current/better/actively maintained smart thermostat?
I’m looking to solve a weird pickle: My HVAC guys installed some booster fans into my ducts because there are a couple that are super long/weird (my house has infinite issues…) but they were unable to be wired directly into the system, so these fans are just plugged into outlets in our “HVAC chamber” in our house. Looking into this after the fact, it seems like there are perhaps some more clever ways they could’ve done this, but I’m a dumb millennial home owner so IDK 
Hence, the hope to smart plug these and get them to turn on/off my way. As of now, they’re just on all the time. The simplest/lamest option would just be to smart plug them and turn the boosters on and off as they feel necessary, but definitely would be cooler to have it smart.
If we’re talking about buying into a system, I think I’d overall be interested in Ecobee and HomeKit, if that’s even possible. I’m guessing I’m looking at some $$$ to start making this stuff happen.
To use HomeKit, you need an iPad that stays in the house, an AppleTV, or HomePod speaker. I have a dozen or so Aqara smart plugs running about doing all kinds of automations. Running automations is super simple.
It seems like you need to pick a smarthome platform that will work best for you then build from there.
Is any one of these better than the other in terms of acting as a hub? I already have a couple Sonos speakers that are working just fine, so it seems like it would make sense to buy an Apple TV… which I don’t even particularly need.
Seems like it would be expensive to “buy in” to HomeKit as a smart home system 
FYI, Apple deprecated using an iPad as a HomeKit hub over 2 years ago (or was it over 1 year ago?)
You’ll need a HomePod (full or mini) or an AppleTV for a minimum HomeKit system.
I’m one of those weirdos that actually prefer Nest Thermostats to Ecobee or any of the (limited) other HomeKit choices.
There is a device called the Starling Home Hub which is a small, palm-sized box that will auto-magically bridge almost all Nest devices into HomeKit.
It works great for my Nest Thermostats and Video doorbells.
I know this sounds like a gushing fan, but I am, as it is truly is a “set it and forget it” box that for $99 I haven’t had to touch in several years.
It just works! (Which is something I CANNOT say about HomeKit which is finicky, flaky, and needs constant TLC to keep running).
Don’t get me wrong, if you want the most natively integrated home automation for a primarily Apple-based home, HomeKit is still the best choice, but it is the least stable and least Apple-like of all Apple tech right now.
(IMHO, having used most systems on the market and supporting a lot of different systems for my clients including custom luxury systems that cost way too much money.)
Absolutely. The most reliable hub for HomeKit is to use an AppleTV, not HomePods.
The HomePods are still using Apple Watch class processor (so grossly underpowered and very low internal RAM memory),
Be sure and use the AppleTV model that has a wired Ethernet port and connect it to your network using wired Ethernet, not Wi-Fi, if at all possible.
Wired connection for your HomeKit Hub greatly increases the reliability and reduces problems versus using it with a Wi-Fi connection.
Some AppleTV models include a “Thread” hardware radio. If you plan to grow your system, a Thread radio gives you a lot more options for additional smart home devices as you grow your system.
(Some entry-level AppleTV models do not include Thread, but I think the version with Ethernet also always include Thread, but don’t have the specs at hand right now.)
Well 
! I missed the memo 
It’s all relative to your situation. Brand new an ATV runs $129 but if it were me I’d eBay that joker.