I have been looking into some low power projects with ESP32 and ESPHome and I want to use ESP-NOW instead of depending on Wifi login to my router.
I saw that there is some development of a component called “WiFi Now” but it is still not available as a stable release. This is the link: https://deploy-preview-775–esphome.netlify.app/components/wifi_now.html
Does anyone know when we will se an implementation of the ESP-NOW functionality?
Yes, I saw that. But it is two years old and there hasn’t been any development in a long time. Adding to that, I have no clue on how to add a custom addon - the same seems to be the case with other people posting in that old tread.
You may wanna try to scroll to the end of the thread linked 
I did before writing my initial post!
First of all I still don’t know how to integrate this component into ESPHome and secondly it is for ESP 8266. I am looking for something that works on ESP32.
To me it looks like it works with esp32 as well with esp8266 and how it should work is well documented too 
I also see the advantages of ESPNOW. When using more devices, it is beneficial to the WiFi routing experience and saves WiFi throughput resources. I came up with an idea to use 2 ESP32s (higher performance). esp32-A is connected to the Internet as a WiFi bridge and communicates with esp32-B through UART or other means. esp32-B is the ESPNOW gateway, which is used to receive data from sub-devices (espnow protocol). I only know how to design hardware, but I don’t know much about it. software programming.
I doubt that esphome devices with native api hog measurable on your wifi network. I have over 150 esphome devices deployed (all connected with the efficiency of the native api to ha) changing them to work with espnow will probably have around 
% of benefit for my wifi network.
The “higher performance” is only a theoretical thing
That is probably not even necessary, one esp is sufficient for that if you stay on the same channel.
Did you see the last post in the linked thread? It has a link to a github which contains this image here:
Looks like this is roughly what you want…
Yes, can it be realized in this way?ESPNOW can also be used as a low-power device,I prefer DIY to buying finished controllers.I have written nearly 100 modules through esphome.Only low-power parts, such as door magnetic sensor and wall wireless switch.
I am looking into low powered devices too. Actually I am doing a mail box project with a ESP32 detecting (with a reed contact) when mail is dropped into the box. A solution with ESP32 in deep sleep mode is not going to work because the ESP32 in deep sleep mode consumes about 9 mA and that will drain a 16850 3400 mAh in just approx. 10 days+. The Wifi Now solution will work much better because I can power down (not deep sleep) the ESP32 and just turn it on for long enough to sendt a call to another ESP32 in my house - working in ESPHome mode. But I need a working Wifi Now component 
I bet it won’t outperform a simple off the shelf aqara door sensor. Why go through all the trouble?
Some people like the trouble… 
That being said, 9 mA in deep sleep is way too high, it should be closer to 10-150µA depending on what peripherals are powered on in deep sleep. I’m guessing you’re using a development board that’s not optimized for power consumption. There’s a lot of info around which ones are low power, and some of them can be lightly modified to reduce consumption (desoldering LED’s etc.).
ESPNow will still markedly reduce your consumption as the connection time is much lower from wakeup to power down though.
My mail box is too far away for an aqara door sensor - tried that and it didn’t work 
Lora seems to be often used for such projects.
I use the deep sleep component of esphome.The esp32 can have a power consumption current of 15uA.I don’t know how your circuit is composed.However, esp32 development board consumes a lot of power.Because the static current of AMS1117 is 5-9mA.If low pow consumption is used,It is suggested to redesign the circuit, It is recommended to use buck boost chip to output 3.3v。I defined io26 as the wake-up pin in esp32.Running current 90mA,Because of this, I want to experience ESPNOW.
What exactly is holding you back trying the latest (last updated yesterday) “ESP Now integration for ESPhome”? 
Because I don’t know how to make these files compatible with my project (ESP32).
Did you read the README.md (specially the chapter Usage) in the github yet?
Yes of cause I read it!
It is easy to follow when it comes to copy the files into the right destination folders, but I have a problem understanding how the code for the example (hub and light) is working. And then it is a little too complicated to change/develop the examples into a simple code for my project.
I want to turn on my ESP32 when the mailman opens the mailbox (my reed contact powers up the ESP32). Then I want to have the “slave” ESP32 to announce it’s presence to the “master” ESP32 in my house, which in turn tells HA that somebody opened the mailbox.
There is a YouTube blogger named mrdiy, or you can go to his website. mrdiy.ca