>USB keyboards do not support more than 6 simultaneous key presses without needing some special workarounds

This isn't totally true. If you want your USB keyboard to work as a boot keyboard (i.e. one that the BIOS understands) then the first 8 bytes of keyboard reports must follow the example (which does have this restriction). After boot though, there will be a Change Protocol request sent from the driver that signals you can use a non-Boot report (which doesn't have this limit).

Alternatively, you can always pack more keys into another report. The BIOS ignores everything beyond the first 8-bytes.