I was very curious about the 6s version as well, so once I asked one seller about this. I asked what MOS driver is used on the ESC. The seller told me it was built with the same BOM as the original one, and he insisted his product runs on 6s. My guess was that they should have done some tests on 6s and didn't end up with magic smoke. Which made them believe it's safe to let the components working under conditions which exceeds the max ratings. Or it wasn't. Maybe someone would buy one, hook up with 6s battery, with the smoke he complained to the seller. The seller told him that it was 6s LFP battery, not li-po.
The CAN bus thing is interesting too. There is one seller selling PCBs and BOM on his shop, he has listed him BOM, and I could find he's using a TJA1050T which requires 5v power supply as CAN transceiver. It's signal level it also 5v which I think it's not safe using with STM32 with (obviously)no level shifters even STM32 is 5v tolerant.
And thanks for explaining your concerns, I think I can call my "cloning" "porting" now