A Schur-type duality between the type B Hecke algebra and a coideal subalgebra of the type A quantum group U arises in our approach (joint with Huanchen Bao) to super Kazhdan-Lusztig theory (this coideal algebra and U form a quantum symmetric pair). Subsequently, this duality is realized geometrically in terms of flag varieties, and a canonical basis for the modified coideal algebra is constructed (joint with Bao, Kujawa, Yiqiang Li). We will review and explain these constructions, and then present a new KLR-type 2-category which categorifies the modified coideal algebra and acts ton a flag 2-category (join with Bao, Peng Shan, Webster).