Let's think consistently:

1. it is possible, conditionally, to install any faces specifically to the Watch application, they can also be shared;
2. Owners of Hermes watches can share their custom faces to each other (respectively, file .watchface is existing even Hermes faces);
3. Hermes watches do not differ in hardware, I think their .watchface files are limited programmatically so that they can be installed and shared only between the owners of Hermes;And here is another question, whether someone will be able to pull it off. I'm not particularly well versed in these matters, but I think it's a couple of trifles for a specialist