Interesting new project to keep those EOL'd Nest Thermostats still useful. I've been struggling on which thermostats to use for a replacement so I'm going to try this first: https://nolongerevil.com
No Longer Evil Thermostat

Repurposing bricked and outdated Nest Generation 1 & 2 thermostats with custom software

Worked perfectly.
Update: now available in Homebridge with an easy to configure plugin: https://github.com/lastowl/homebridge-nolongerevil-nest#readme
@stucki my 3rd gen model is still supported but I’d almost rather get it on something like this. I look forward to updates you may have
@joshcalvetti I have one gen 3 and definitely had the same thought.
@stucki I’ve already had to hack it into HomeKit, which is tedious and frustrating when it gets out of whack. I’d much rather have one last thing to be fighting!
@stucki awesome. Can't wait to play after I remove from (manual) use
@john why wait? Everything remains the same on the thermostat. This just gives you some remote access.
@stucki because i have replacements in the mail already because I'm mad at Google for everything about Nest but I really do want to play with this :)