u/InherentlyListless

We are traveling to Seoul at the end of March and will only have 2 full days and 2 partial travel day. I am looking for suggestions of cool things to do. My niece and I are KPOP fans, and we are Muslim so looking for both family friendly activities and also ones were you can have sober fun. Are there any must see / must do activities, live music venues, places to get both Unique and Useful souvenirs? I think one thing we want to do for sure is Hanbok rental and visiting historical sites and other immersive ideas like that would be appreciated. Is there anything that you did there that was particularly memorable?