I doubt we'll ever get an underwear shoot of him, especially while he's still part of Seventeen, they got a lot of sensitive stans. Not even the most exhibitionists Idols like Wonho or Minhyuk have done it, Jungkook also had a CK campaign and there was no underwear shoot, I guess it's a hard NO NO in kpop industry (while jpop idols are out there showing their full asses to the world). Considering Korea's alarming free falling birth rate perhaps they should reconsider it and start some more intensive whoring spicy advertisements of their men.
The only "idols" I can recall to have done it were Mark Tuan and Yixing, but it's also debatable whether they were really idols or not at that point since Mark Tuan had left GOT7 previously and seemed focused on a more US career and Yixing was already established in his solo career in China (his case is the most interesting to me, China is known to be very conservative and censorious with their media but they had no problem with a huge celebrity starring an underwear campaign lol).