Do any of the manufacturers, available to the public, make their cells close enough to matter? From what I've read if all the cells in a pack are within 1% or less of each other in IR and Capacity you can bypass the whole cell level bms/monitoring issue and simply treat the pack as one big HV battery. Only worrying about over charging/discharging on the pack level and not the cell level. After an initial balance, either top or bottom, of course.