Ok, we all get the world is moving to an IOT. The thing is my TV crashes, my cellphone gets updates 1 to every 4 weeks, great, but for things like fridges, toasters, dumb items, why update without a major reason, (and hassle to go thru).
Using Pi’s, and other linux(ish (add all flavors here)) are subject to mass use, and, therefore, once a flaw is discovered, well, all fall infected, and its 50% split between if all the devices fall infected if there mal-performance is worse, or the assisting in a broader attack.
For general IOT, I love the fact firmware needs to be “flashed”, (vs a loaded file system, a simple file copied), and a two processor check, (which has been used in space travel, aviation, ect, as a very proven tech, (and yes, someone will probably point out 3 or even 4 processors), the point is, a different approach to getting hacked.
I just don’t see, if you understand every line of code from a-z, for limited iot projects, its not more secure than using linux code updated dately.
depend on your choice and your “IDEA” how to do it …
i’m using RaspberryPi Zero as Mosquitto MQTT Broker for my home tests (and work prety well)
also in Android i installed MQTT DASH too.
I’m using also MQTTnet (taken there GitHub - dotnet/MQTTnet: MQTTnet is a high performance .NET library for MQTT based communication. It provides a MQTT client and a MQTT server (broker). The implementation is based on the documentation from http://mqtt.org/.) and did a little modify
for usage with MS SQL (I’m still working on ASP.NET Part to register devices etc ,).
and i’m working on this too (how to save certificate on this device)
https://github.com/esp8266/Arduino/tree/master/libraries/ESP8266WiFi/examples/HTTPSRequestCACert
and this how to make an configurable external device (out of my development board)
and to create an ESP8266 WiFi (with TLS 1,2 CERTIFICATE MQTT middle wire between my device) for/and MQTT BROKER with secure connection.
and my main Idea i’ve got there
so now i’m going to prepare how to use ESP8266 (or ESP8285) with .NET (Micro Framework ,TinyCLROS even NanoFramework too) throught JSON (no need more external internet ,and other things regards networks because all jobs will be done with ESP82xx Wifi)
this is my way 
so i’m not going using Linux but more “device’ ESP8255 or ESP8266 (with more space and capability for secure connection if it missing i’m going to create it”
and using OpenSSL it did job for me enought .
Valon, check out Tasmota for the ESP8266. Pretty comprehensive and supports many of the Sonoff devices too. I reprogrammed my Sonoff B1 LED lamps and now I can control them via MQTT. They were useless before as only the phone app would work.
thanx ,I checked and used (too) SonOff products and flashed them with UART and without problem used with Raspberry PI MQTT Broker and MQTT Dash Phone (without need for outer server) for home,
but my primary goal is to use .NET “on/for those device” so for that i’m working on
ESP82xx to create and firmware with API access “which will coummunicate with devices” throught UART “JSON” as universal approach between Devices and EndPOINT.
example: Device1 (TinyCLROS/.Net Mf / nanoFramework) handle well UART (but i need to include JSON) so that is enought to using WiFI (ESP82xx with API and access done inside ESP82xx) to connect at EndPOINT in this case MQTT Broker (but i’m seeking also to include other protocols such are websoket/https/Azure with TSL 1.2) so in this way Device1 will be used more for sensors than for Network because for Network will take care ESP82xx(with their looping inside) this is a reason why i published sample links (Arduino sample - to make an version for .NET) when i’ve got idea,and ESP82xx sample for web configuration (how to configure as outer system via web without need to change or intervene on ,NET firmware) because ESP8266 E12 (is cheap and have enough memory/flash) ability to store certificate/config data etc.
but how i will have success time will tell “wrong or good” 