ESP-Now VS Tasmota

There's some other good tutorials for it as well, https://randomnerdtutorials.com/?s=esp-now and https://github.com/HarringayMakerSpace/ESP-Now

For power, I'd recommend Li-Ion primary (non-rechargeable) cells, whatever size works best for you. Those have essentially zero internal leakage and a 5 year shelf-life. If you've done it all correctly, it's conceivable it could be 5 years before you need to change the batteries (on top of a 30' ladder). You'd need a small high-efficiency buck converter to drop the 6.8V batteries down to 3.3V for the ESP, with a separate switched 5V linear regulator (one with a SHUTDOWN pin) to power the servos when they need to be driven. The ESP will consume 16-20uA in Deep Sleep, and the buck converter should mostly be off, except for when the ESP wakes every 3.5 hours (maximum Deep Sleep interval). If you're already using ESP-NOW to talk to the vent ESPs, then you could do a 'vent changed' check every time it wakes, otherwise it's more efficient to go back to Sleep quickly and wait until 12-24 hours has elapsed before you fire up a full WiFi connection. Not counting buck inefficiencies and servo movements, the ESP would only consume about 175mAh per year. The batteries will expire before they empty, maybe in 6-7 years.

I presume you've seen Anthony Elder's examples? He got a single ESP to act as hub by restarting it. In a low-traffic environment that'd work. There was discussion and a new PR to speed up the reconnect time using WIFI_RESUME that's been merged in the git repo, which should make a single-ESP hub faster to respond. You'd need a little fault checking in case the BSSID changes of course, but for the normal case things would be faster.

All of my office devices are connected to Sonoff S31 smart plugs, flashed with Tasmota on their own locked-down VLAN, and can be controlled via voice, Alexa, Tasker automation on my Android, NFC tags at my office door and various scripts triggered via my StreamDeck (on Linux). This all works fantastic, and I can turn on or off my devices, including my printer, when I start or end my day at work.

The best alternative firmware example for true IOT devices is Tasmota [1]. Erase manufacturer firmware for every ESP devices the day after purchase to avoid those careless manufacturer firmwares.

[1] https://tasmota.github.io/docs/

The ESP8266 based Sonoff S31 and ESP32 based Switchbot plugs, both flashed with either Tasmota or ESPHome, are my go-to options for US WiFi smart plugs with power monitoring.

And if you want to turn your ESP8266 into a standalone appliance, with a web interface and directly editable config that doesn't need a build step, Tasmota is another great option.

https://tasmota.github.io/docs/