generic IoT component with open-standard authenticated comms
a lot of these generic devices do exist: thermostats, humidity, etc. - well, basically any sensor -
but their supplier is currently China via eBay (where there are some annoying compatibility problems with counterfeit gear). They are very much DIY, arduino+RPi projects. Very botnet resistant.
The sensor mesh comms can be authenticated/signed [but not encrypted so as to avoid TLA aggression] MITM is vaguely possible (https://github.com/Yveaux/NRF24_Sniffer), I did have some success at that, but I don't really mind my neighbours knowing that
0;0;3;0;9;read: 105-105-0 s=255,c=3,t=12,pt=0,l=3,sg=0:1.0_105;255;3;0;12;1.0
is my current status, provided that only I can change it. [protip - consider changing this in MySensors library MyConfig.h
// Key to use for HMAC calculation in MySigningAtsha204Soft (32 bytes)
#define MY_HMAC_KEY 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 - to something a little less predictable]
more at
https://forum.mysensors.org/topic/1021/security-introducing-signing-support-to-mysensors/2
'nother tip, I found the semiconductor pressure sensor for arduino IoT so sensitive, such high resolution, that it does the whole 'house alarm' system in a single component. It's been fairly easy to correlate the 'nano'-changes in domotic atmospheric pressure with a particular door or window open or almost which specific person (or cat) is walking in the room! no-need for door/window vibration sensors - just sample the atmosphere
These DIY systems are potentially a lot better than cloud-based NESTy things, but aren't yet ready for wide deployment, need a few more person-years of testing & experimentation before release