If you mean sending a message from an external device to the watch and running some python code with it then yes.
That is cool. I don't see iPhone there, does it mean notifications aren't supported there?
I dont know what the notification features are with the stock firmware and TBH it is a hit and miss affair with all devices and you have to do plenty of research before buying.
The device I quoted is ripe for hacking and currently the waspos firmware is a blank slate for anyone to create custom watch software.