I suspect that whoever makes the film does the packaging. Maintaining a facility capable of slitting bulk rolls, packing 35mm into cassettes, canisters and boxes as well as create 120 film, attach it to paper, roll it unto rolls, attach the foil and place it in a box is a very complicated undertaking. To do so for one small mail order company only makes little sense. I don't think there is much or a market for doing this for others, especially in the US. If a company was willing to do that for others, it would really have helped Film Ferrania get up and running faster.
My experience is that UltraFine Xtreme films looks a lot like Kentmere, and nothing at all like Foma films. I have no experience with Innoviscoat B&W films. On the other hand, most of my Harman manufactured products have been labelled as "Made in England". Maybe made in UK is designed to through people off