I've never tried Knoppers or this Nut Bar variant, so have no idea what they're like (maybe like a Bueno bar?)
Google Images comes up with foreign packs - but this Facebook page
(Sweet Reviews UK - where I sourced some pictures) suggests they appeared in Aldi/the UK around November 2020.
Think this will be National, though you can never be sure.
This Aldi store has the Titan Ice Cream Bars back in stock again (Mars Bar Ice Cream knockoffs - highly recommended and purchased!) - though they're predicting snow in Glasgow tonight