Given the truly enormous cost of the machinery to manufacture handlebars, it is unlikely that hope will start making them in their own factory with their own staff etc. How much of an input they have into who they commission to make bars for them is another thing though. fwiw they don’t make all the components in their lights from scratch themselves either but they are pretty good and pretty reliable. This would be in part because their design of the battery boxes and lamp bodies keep them cool keeps the elements out, but also they will have been careful not to just go for the cheapest cells/leds/pcbs etc but the better performing ones.
If you read the Thomson blurb they would like us to think that their standards and r&d are the same for their (outsourced) handlebars as the things they make (ie mill from billet, much like pretty much everything hope do) themselves. iirc thomson invested in some advertising/info-mercial stuff around their handlebars as it was a bit of a departure for them.