The smallest ESP32 I have is a Atom S3 Lite, but it’s still significantly larger than you specs (24x24x9.5mm). Not cylindrical, but on my end I fit it easily in 25mm diameter hole. The advantage is that it comes with a case :).
Be aware that it’s not a well supported device yet and you should look at this thread M5stack Atom S3 Lite (which compile settings?) - Totally freaking out after 3 night/days - #10 by dr1rrb