Thanks for visiting the Community forum.
We understand that you'd like to activate a countdown timer after your Smart Life switch turns on. While the specific feature you're asking for is unavailable, I highly suggest sharing feedback about it with our product engineers, who continuously work on improving the features on our devices.
If you have other questions in mind, let me know; otherwise, I'll be locking this thread in the next 24 hours.
We can only provide you with a list of third-party manufacturers that work with Google since we don't recommend specific switches. You can explore this website for more information.
Let me know if you have additional questions.