Would this design for Li-Ion cell protection+balancing circuit work?
I believe this would work, but you may want to consider a protection chip like https://www.ti.com/document-viewer/BQ294533/datasheet/abstract#SLUSAJ36867 as it requires less external transistors, or one with internal transistors, which may save space in a constrained application like a cubesat. Test it thoroughly, simulate various failures.