OnePlus has never been one to squander its efforts, nor overreach too much into odd and new tech fields, like Xiaomi. On the contrary, the start-up has always been keenly focused on mobile alone, which has undoubtedly helped in creating its compelling smartphone offers at least to some extent.
Rumors of various other OnePlus devices have been a constant recurrence over the years, but never really came to be, apart from the April Fools day OnePlus DR-1 limited production mini drone, if you want to count that. However, a new tweet by co-founder Carl Pei definitively proves that this product strategy wasn't always set in stone and that he company has explored other ideas in the past.
The post in question showcases an early sketch of what could have been a OnePlus smartwatch. The company was apparently exploring the idea in between the release of the OnePlus 2 and the new OnePlus 3 flagships. The device looks to offer a round form factor and interchangeable bands with what looks to be a sort of snap-in frame design.
Not much else is mentioned about it, but judging by Carl Pei's comment - "What could have been but never will be.", it is largely irrelevant, since the smartwatch is apparently scrapped for good.
someday someone or another company will steal this ideas and make it them.. sueing drama will happen.. hhaa
probably, although claiming "will never be" and then saying "hey we made it" would be really bad for credibility... i think it's just a way of saying "we were half way there" XD