I have it! Pretty fun to play with, although I am not experienced in C++ so have not been able to make it do super useful things yet. It is also quite fiddly - I think it would take quite a lot of work for it to be useful as a daily driver.
Here are some useful starting points if you want to play with it:
I've been using ESP8266es and ESP32s for years and Lua isn't really that popular. The original NodeMCU did come with Lua, but I've never used it (I just flashed something else as soon as I got them) and I don't know of many people using it either.
I'd say that MicroPython is more popular than Lua at this point.
ESP32 in deep sleep modes is reasonably battery friendly (all depending on your frame of reference, of course.) 5uA in RTC-only and 10+ uA in RTC+ULP sleep.
Presumably for a watch use case, you'd plan to deep sleep (ULP) or hibernate (RTC) 98+% of every minute and turn the radios on as infrequently as you could stand to get external notifications. I don't need split-second precision on my notifications if the alternative is a much longer battery life.
You can use the ESP32 onboard RTC to do periodic wakeups. (You can also use external stimuli via GPIO pins, but you don't need anything extra if all you want is a periodic wakeup.)
This might be more up my alley because of WiFi. The only reason I'd want a wearable is to be able to put down my phone but still get notifications(and maybe reply to messages) and Bluetooth's range limits that. But honestly, I hate wearing watches.
Here are some useful starting points if you want to play with it:
Instructions for setting up a platform that easily allows you to build your own simple apps for it: https://www.instructables.com/Lilygo-T-Watch-2020-Arduino-Fr...
Extended version of the platform with many included apps and features: https://github.com/wfdudley/T-watch-2020
MicroPython port for the watch (have not been able to try it yet and not sure if it is maintained): https://github.com/OPHoperHPO/lilygo-ttgo-twatch-2020-microp...