Toyota has designed and built that vehicle for that SEA market. Sure could it sell in the US? To some who want that, but the US is over-served for pickup trucks (granted not at that Hilux Champ price point.)
Toyota has spent a lot of money to build the Tacoma and Tundra in the US because Americans want vehicles built in America (plus the chicken tax.) There's little reason to import the Hilux Champ, especially now in light of the additional US tariffs not to mention that it would not pass all of the required regulations that the US has.
It's true that these trucks wouldn't be marketable in the U.S. based on safety or emissions, though I imagine it wouldn't require that many modifications if there were a consumer market.
The problem is that if safety and emissions equipment raise the price to $20k, and you add the 25% chicken tax, you are at the $25k of a barebones Ford Ranger.
I feel the chicken tax really should be repealed. It has been distorting the U.S. truck market for 40 years, preventing smaller, cheaper, more fuel efficient trucks from asian manufacturers from competing.
Toyota has spent a lot of money to build the Tacoma and Tundra in the US because Americans want vehicles built in America (plus the chicken tax.) There's little reason to import the Hilux Champ, especially now in light of the additional US tariffs not to mention that it would not pass all of the required regulations that the US has.