|Maybe, maybe not.|
Turns out that the Apple Watch has a secret hiding in its developer port, which itself is hidden in the attachment point for the Watch's bands. It is possible to charger via a physical connection, as well as the Qi connection on the rear plate.
This opens up all kinds of possibilities for bands with batteries or charging connections exposed to the outside world. One watch band manufacturer - Reserve, discoverer of the capability - intends to rejig its planned battery band to use the port.
Now, placing the port where it is on the Watch strongly suggests that Apple may have had this in mind for a future development. Or may have had it in mind for launch and decided to cancel the feature at the last moment. Whatever the truth basing a project on an undocumented feature which could be disabled by Apple through software doesn't strike me as a particularly clever thing to do.
Not that I think it represents a risk to the Watch itself, but if the Reserve were to prove successful and then Apple were to throw the kill-switch the company would saddle itself with a heap of disgruntled customers, a possible barrel-load of returned hardware and a damaged brand.
On the other hand if Apple are planning on allowing this port to be used for charging then you can be sure that it will want to vet products to ensure they aren't going to damage a customer's Watch. This suggests that a certification programme, along the lines of MFi, could be in the offing. Whether this will be backed with DRM remains to be seen.
In either case I'd tread very carefully before buying the Reserve, because you may end up with a pointlessly heavy watch strap that doesn't do what you bought it for.