JWST is likely to become one of the most important sources, if not far and away the most important source, of information about KBOs, which are hard to visit, but can easily be observed with the remarkable spectral resolution of JWST. Here are a couple of major results which haven't been posted here previously.

CO and CO2 ices
https://iopscience.iop.org/article/10.3847/PSJ/ace2ba

CH4, C2H2, C2H4, and C2H6 on Sedna, Gonggong, and Quaoar
https://phys.org/news/2023-10-jwst-kuiper-b...a-gonggong.html