This is exciting for me only because I've been amassing a collection for their batteries, and not I also have a decent amount of boards & displays that go with them. I've been meaning to probe around on them but I've not had the time
If you're trying to daily drive it, I'd recommend strongly against it. It'll be an absolutely miserable experience for you, and probably will be quite slow even if you're using it as a wall display.
That being said, this xda post seems to still have a live file. Hopefully it's what you need
What was the update? Getting address not found on both calyos.org and calyxinstitute.org which doesn't bode well
Edit: came back up. Update if it's down when viewed
Update: August 27 2025
We are concerned that some users may have not seen the important message in this letter about CalyxOS’ current hiatus. Therefore, we are rolling out one last OTA update to devices currently running CalyxOS to reach as many active users as we can. You can read our post for more details about this update.
https://support.google.com/googlenest/answer/16233096 1st and 2nd gen learning thermostats are going EOL by October 25th without any option to control locally (other than, yknow, the thermostat itself)
But don't worry! They'll let you purchase the 4th gen for only $149.99 if you're one of these owners!! Yippee!!!