A Swiss journal reported about this as they identified and interviewed the watchmaker: https://www.letemps.ch/economie/horlogerie-joaillerie/donald-trump-propose-desormais-une-montre-swiss-made-a-100-000-dollars-dotee-d-un-mouvement-chaux-de-fonnier
However the article is ambiguous about what is actually made in Switzerland, sometime describing it as “the mechanism” and sometime as “the watch”.
Thanks hadn’t laughed like that in a while xD