Since Apple first launched the Apple Watch, it has not allowed third-party developers to create and launch their own custom faces for the device. That could change, according to the code in the developer's latest version, discovered by 9to5Mac.
9to5Mac discovered the code in watchOS 4.3.1, which includes some advice about what will come in future updates, such as warnings for old applications, as well as a log message that says "this is where generation of third-party configuration packages would occur. "That's just a placeholder reference, but it seems that Apple could allow developers to make their own watch faces at some point in the future. There is no indication of when Apple will allow this to happen, but it seems to be a step in the right direction for those who are bored with current options.
Last year, Apple unveiled the current watchOS during the 2017 World Developers Conference, and is expected to unveil watchOS 5 at this year's WWDC on June 4.